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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 Central

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

    2002-01-01

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

  5. 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…

  6. 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

  7. Mercury's Messenger

    ERIC Educational Resources Information Center

    Chapman, Clark R.

    2004-01-01

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

  8. 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...

  9. MESSENGER: Science payload status

    NASA Astrophysics Data System (ADS)

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

    2003-04-01

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

  10. 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.

  11. 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.

  12. 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

  13. 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...

  14. 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

  15. 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

  16. 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.

  17. 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.

  18. 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.

  19. 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

  20. 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

  1. The Magnetometer Instrument on MESSENGER

    NASA Astrophysics Data System (ADS)

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

    2007-08-01

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

  2. MESSENGER'S First and Second Flybys of Mercury

    NASA Technical Reports Server (NTRS)

    Slavin, James A.

    2009-01-01

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

  3. Canine procalcitonin messenger RNA expression.

    PubMed

    Kuzi, Sharon; Aroch, Itamar; Peleg, Keren; Karnieli, Ohad; Klement, Eyal; Dank, Gillian

    2008-09-01

    Procalcitonin is considered an acute phase protein used as both a marker of infection and prognosis in human medicine. Canine procalcitonin has been previously sequenced; however, its use as a diagnostic or prognostic tool in dogs has never been assessed. A quantitative reverse transcription polymerase chain reaction (qRT-PCR) assay for canine procalcitonin messenger RNA (mRNA) was developed. Whole blood samples were collected from ill and healthy dogs. RNA was extracted and the real-time PCR was assessed. The patients' diagnoses, complete blood cell count, and differential leukocyte count results were recorded. Based on the diagnosis, dogs were divided into 5 groups: inflammatory, infectious, neoplastic, other diseases, and healthy controls. Procalcitonin mRNA expression and the hematological measures were compared between groups, and their correlations were assessed. Procalcitonin mRNA expression was assessed in 70 dogs, including infectious (17), noninfectious inflammatory (17), neoplastic (18), other diseases (7), and healthy controls (11), and was significantly (P < 0.001) higher in all ill dogs versus controls. Procalcitonin may therefore be considered an acutephase protein in dogs. However, there were no significant differences in procalcitonin mRNA expression between ill dog groups and no correlations between its expression levels and hematological measures. In 5 dogs of all disease categories, procalcitonin mRNA expression was measured twice during the course of disease. The changes in its levels were in agreement with the clinical evaluation of improvement or deterioration, suggesting a possible prognostic value. PMID:18776098

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

    PubMed Central

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

    2008-01-01

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

  5. Endogenous Arabidopsis messenger RNAs transported to distant tissues.

    PubMed

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

    2015-01-01

    The concept that proteins and small RNAs can move to and function in distant body parts is well established. However, non-cell-autonomy of small RNA molecules raises the question: To what extent are protein-coding messenger RNAs (mRNAs) exchanged between tissues in plants? Here we report the comprehensive identification of 2,006 genes producing mobile RNAs in Arabidopsis thaliana. The analysis of variant ecotype transcripts that were present in heterografted plants allowed the identification of mRNAs moving between various organs under normal or nutrient-limiting conditions. Most of these mobile transcripts seem to follow the phloem-dependent allocation pathway transporting sugars from photosynthetic tissues to roots via the vasculature. Notably, a high number of transcripts also move in the opposite, root-to-shoot direction and are transported to specific tissues including flowers. Proteomic data on grafted plants indicate the presence of proteins from mobile RNAs, allowing the possibility that they may be translated at their destination site. The mobility of a high number of mRNAs suggests that a postulated tissue-specific gene expression profile might not be predictive for the actual plant body part in which a transcript exerts its function. PMID:27247031

  6. 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.

  7. 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.

  8. 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…

  9. 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

    ... in the Federal Register on March 5, 2010 (75 FR 10321). The workers are engaged in employment related... Capital, MagRabbit, Manpower and Spherion Corporation; Round Rock, TX; Dell Products LP--Parmer North One... Capital, MagRabbit, Manpower, and Spherion Corporation, Round Rock, Texas (TA-W-72,150) and Dell...

  10. MESSENGER at Mercury: Early Orbital Operations

    NASA Technical Reports Server (NTRS)

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

  11. 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

  12. 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

  13. Attitude Sensor and Gyro Calibration for Messenger

    NASA Technical Reports Server (NTRS)

    O'Shaughnessy, Daniel; Pittelkau, Mark E.

    2007-01-01

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

  14. MESSENGER Observations of Substorm Activity at Mercury

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

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

  15. Mercury's Na Exosphere from MESSENGER data

    NASA Astrophysics Data System (ADS)

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

    2012-10-01

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

  16. 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.

  17. 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)

  18. 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.

  19. 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.

  20. 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.

  1. 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].

  2. 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

  3. Imaging During MESSENGER's Second Flyby of Mercury

    NASA Astrophysics Data System (ADS)

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

    2008-12-01

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

  4. 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.

  5. Cosmic muons, as messengers from the Universe

    NASA Astrophysics Data System (ADS)

    Brancus, I. M.; Rebel, H.

    2015-02-01

    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.

  6. 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.

  7. 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

  8. Theory of high-energy messengers

    NASA Astrophysics Data System (ADS)

    Dermer, Charles D.

    2016-05-01

    Knowledge of the distant high-energy universe comes from photons, ultra-high energy cosmic rays (UHECRs), high-energy neutrinos, and gravitational waves. The theory of high-energy messengers reviewed here focuses on the extragalactic background light at all wavelengths, cosmic rays and magnetic fields in intergalactic space, and neutrinos of extragalactic origin. Comparisons are drawn between the intensities of photons and UHECRs in intergalactic space, and the high-energy neutrinos recently detected with IceCube at about the Waxman-Bahcall flux. Source candidates for UHECRs and high-energy neutrinos are reviewed, focusing on star-forming and radio-loud active galaxies. HAWC and Advanced LIGO are just underway, with much anticipation.

  9. 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

  10. 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.

  11. 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

  12. 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

  13. 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

  14. 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.

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

    ERIC Educational Resources Information Center

    Grantham, Barry

    2001-01-01

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

  16. First MESSENGER orbital observations of Mercury's librations

    NASA Astrophysics Data System (ADS)

    Stark, Alexander; Oberst, Jürgen; Preusker, Frank; Peale, Stanton J.; Margot, Jean-Luc; Phillips, Roger J.; Neumann, Gregory A.; Smith, David E.; Zuber, Maria T.; Solomon, Sean C.

    2015-10-01

    We have coregistered laser altimeter profiles from 3 years of MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) orbital observations with stereo digital terrain models to infer the rotation parameters for the planet Mercury. In particular, we provide the first observations of Mercury's librations from orbit. We have also confirmed available estimates for the orientation of the spin axis and the mean rotation rate of the planet. We find a large libration amplitude of 38.9 ± 1.3 arc sec and an obliquity of the spin axis of 2.029 ± 0.085 arc min, results confirming that Mercury possesses a liquid outer core. The mean rotation rate is observed to be (6.13851804 ± 9.4 × 10-7)°/d (a spin period of 58.6460768 days ± 0.78 s), significantly higher than the expected resonant rotation rate. As a possible explanation we suggest that Mercury is undergoing long-period librational motion, related to planetary perturbations of its orbit.

  17. 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.

  18. 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.

  19. MESSENGER's use of solar sailing for cost and risk reduction

    NASA Astrophysics Data System (ADS)

    O'Shaughnessy, Daniel J.; McAdams, James V.; Bedini, Peter D.; Calloway, Andrew B.; Williams, Kenneth E.; Page, Brian R.

    2014-01-01

    The MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) mission used six planetary gravity assists in order to enable capture into orbit about Mercury. A key element of MESSENGER's successful trajectory was achieving the proper gravity assist from each planetary flyby. The criticality of the MESSENGER gravity assists levied tight accuracy requirements on the planetary-flyby targeting. Major errors could have precluded Mercury orbit insertion or required modifications to the trajectory that increased mission complexity, cost, and risk by requiring additional Mercury flybys and extending mission duration. Throughout the mission, MESSENGER modified its strategy for achieving accurate planetary flybys. By using solar sailing, the MESSENGER team was able to eliminate all of the flyby approach maneuvers without sacrificing flyby accuracy, thereby saving mission ΔV margin. The elimination of these approach maneuvers also markedly reduced mission risk, as these approach maneuvers were nominally planned during a time of heightened sensitivity to errors and precluded unique flyby science opportunities. The paradigm shift used by MESSENGER may be useful for other interplanetary missions, particularly if their trajectories require gravity assists in the inner solar system.

  20. 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

  1. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

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

  3. Thermal evolution of Mercury as constrained by MESSENGER observations

    NASA Astrophysics Data System (ADS)

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

    2013-05-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

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

  5. 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

  6. 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…

  7. 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…

  8. 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…

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

    NASA Technical Reports Server (NTRS)

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

    2008-01-01

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

  10. 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…

  11. Launch and Early Operation of the MESSENGER Mission

    NASA Astrophysics Data System (ADS)

    Holdridge, Mark E.; Calloway, Andrew B.

    2007-08-01

    On August 3, 2004, at 2:15 a.m. EST, the MESSENGER mission to Mercury began with liftoff of the Delta II 7925H launch vehicle and 1,107-kg spacecraft including seven instruments. MESSENGER is the seventh in the series of NASA Discovery missions, the third to be built and operated by The Johns Hopkins University Applied Physics Laboratory (JHU/APL) following the Near Earth Asteroid Rendezvous (NEAR) Shoemaker and Comet Nucleus Tour (CONTOUR) missions. The MESSENGER team at JHU/APL is using efficient operations approaches developed in support of the low-cost NEAR and CONTOUR operations while incorporating improved approaches for reducing total mission risk. This paper provides an overview of the designs and operational practices implemented to conduct the MESSENGER mission safely and effectively. These practices include proven approaches used on past JHU/APL operations and new improvements implemented to reduce risk, including adherence to time-proven standards of conduct in the planning and implementation of the mission. This paper also discusses the unique challenges of operating in orbit around Mercury, the closest planet to the Sun, and what specific measures are being taken to address those challenges.

  12. 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.

  13. 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

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

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... MESSENGERS, LEARNERS (INCLUDING STUDENT-LEARNERS), AND APPRENTICES Messengers, Learners (Excluding Student... be filed by an employer or group of employers. Preferential consideration will be given...

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

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... MESSENGERS, LEARNERS (INCLUDING STUDENT-LEARNERS), AND APPRENTICES Messengers, Learners (Excluding Student... be filed by an employer or group of employers. Preferential consideration will be given...

  16. 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

  17. 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

  18. 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.

  19. 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

  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. Calibration of the MESSENGER X-Ray Spectrometer

    NASA Astrophysics Data System (ADS)

    Starr, Richard D.; Schlemm, Charles E., II; Ho, George C.; Nittler, Larry R.; Gold, Robert E.; Solomon, Sean C.

    2016-03-01

    The X-Ray Spectrometer (XRS) that flew on the MESSENGER spacecraft measured X-rays from the surface of Mercury in the energy range ~1-10 keV. Detection of characteristic Kα-line emissions from Mg, Al, Si, S, Ca, Ti, and Fe yielded the surface abundances of these geologically important elements. Spatial resolution as fine as ~40 km (across track) was possible at periapsis for those elements for which counting statistics were not a limiting factor. Four years of orbital observations have made it possible to generate from XRS spectra detailed elemental composition maps that cover a majority of Mercury's surface. Converting measurements to compositions requires a thorough understanding of the XRS instrument capabilities. The ground and flight calibration measurements presented here are necessary for the reduction and analysis of the X-ray data from the MESSENGER mission.

  3. 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.

  4. 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.

  5. 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.

  6. MESSENGER Observations of Cusp Plasma Filaments at Mercury

    NASA Astrophysics Data System (ADS)

    Poh, Gangkai; Slavin, James; Jia, Xianzhe; DiBraccio, Gina; Raines, Jim; Imber, Suzanne; Gershman, Daniel; Anderson, Brian; Korth, Haje; McNutt, Ralph; Solomon, Sean

    2015-04-01

    The MESSENGER spacecraft, in orbit about Mercury, has documented highly localized, ~1-2-s-long reductions in the dayside magnetospheric magnetic field of the planet with amplitudes up to 90% of the ambient intensity. These magnetic field depressions which we have termed cusp filaments are observed from just poleward of the magnetospheric cusp to mid-latitudes, i.e., from ~55 to 85oN. Minimum variance analysis and superposed epoch analysis of the Magnetometer (MAG) data indicate that the filaments are simple two dimensional flux tubes. If the filaments move over the spacecraft at the polar convection speed, then these filaments have a mean diameter of ~230km, which is an order of magnitude larger than the gyro-radius of a 1 keV H+ ion, i.e., ~ 23 km. During these events, MESSENGER's Fast Imaging Plasma Spectrometer (FIPS) measured H+ ions with magnetosheath-like energies consistent with the view that the magnetic field depressions are diamagnetic and most probably the low-altitude extensions of flux transfer events (FTEs) that form at the magnetopause as a result of reconnection. Here we analyze 349 filaments identified in MESSENGER magnetic field and plasma data to determine the physical properties of these structures. MESSENGER observations during the spacecraft's final low-altitude campaign confirm that these cusp filaments extend down to very low altitudes. We calculate an average particle precipitation rate onto the surface from all of the filaments at any given time of ~ 2x1025 #s-1. This precipitation rate is comparable to published estimates of the total precipitation rate in the cusp proper. The existence of these cusp filaments has important implications for surface sputtering and our understanding of Mercury's northern cusp. Overall, the MAG and FIPS observations analyzed here appear consistent with an origin for cusp plasma filaments by the inflow of magnetosheath plasma associated with the localized magnetopause reconnection process that produces FTEs

  7. 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

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

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

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

  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. 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.

  11. 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.

  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. 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…

  14. An Overview of MESSENGER's First Encounter with Mercury's Magnetosphere

    NASA Astrophysics Data System (ADS)

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

    2008-05-01

    As the MESSENGER spacecraft performed a gravity assist at Mercury on 14 January 2008, observations were made of Mercury's magnetic field, plasma, and energetic particle environment, including the first-ever ion observations at the planet. Mercury's magnetosphere presents a particularly stiff test of theories of the solar wind interaction with magnetized bodies because both the spatial and temporal kinetic and fluid scales overlap to a considerable degree. This overview provides the context for detailed analyses of the many varied phenomena observed as well as quantitative comparisons with fluid and hybrid simulations of Mercury's magnetosphere for this encounter. The magnetosphere was not as dynamic for MESSENGER's first encounter as it was for the comparable Mariner 10 encounter I. The MESSENGER trajectory passed through the system from the nightside dusk flank, across midnight near the planet, and through the bow shock in the morning sector. The inbound shock crossing was typical of flank shocks at smaller obstacles, but there was a prolonged period of intense magnetic turbulence in the sheath prior to the magnetopause crossing, including multiple flux rope signatures. The inbound magnetopause transit occurred near the center of the tail and included structures indicative of Kelvin-Helmholtz instability at the flank magnetopause. Multiple inclusions of proton plasmas were found close to the planet. Three distinct transitions were observed on the outbound trajectory. The first is attributed to an outer layer of solar wind plasma within the magnetosphere. This was followed by a well-defined magnetopause and subsequently by an encounter with a shock displaying many features of a dynamic re-formation typical of quasi- parallel shocks.

  15. 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.

  16. MESSENGER Observations of Cusp Plasma Filaments at Mercury

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

  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. 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.

  20. The X-Ray Spectrometer for Mercury MESSENGER

    NASA Technical Reports Server (NTRS)

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

    2001-01-01

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

  1. 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.

  2. MESSENGER at Mercury: A mid-term report

    NASA Astrophysics Data System (ADS)

    Bedini, Peter D.; Solomon, Sean C.; Finnegan, Eric J.; Calloway, Andrew B.; Ensor, Susan L.; McNutt, Ralph L.; Anderson, Brian J.; Prockter, Louise M.

    2012-12-01

    After almost 5 years in development and more than 6 and a half years in cruise toward its destination, NASA's MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft finally entered orbit about Mercury on 18 March 2011, initiating a 1-year, focused investigation of the innermost planet. Operating from a highly eccentric orbit designed to keep the spacecraft safe and to facilitate the required observations, MESSENGER is using its payload of seven instruments and the spacecraft's radio-frequency telecommunications system to characterize the planet's interior, surface, atmosphere, and magnetosphere. The demands of the many measurements needed to meet the program objectives, coupled with the constraints associated with spacecraft safety and the orbital geometry, led to the adoption of an automated science-planning tool to optimize science data collection. The tool was used to design the entire year of observations prior to orbit insertion and has the capability of regenerating the plan quickly in response to anomalies in flight (e.g., spacecraft safe-mode demotions) or on the ground (e.g., missed Deep Space Network tracks). Because one Earth year spans two Mercury solar days, there are two opportunities in the course of MESSENGER's science data-collection campaign to observe any specific location on the planet with a given viewing geometry. To take advantage of this schedule, the science plan was divided into two parts. During the first solar day, priority was given to producing global map products. The second day will be used to focus on specific targets and to recover observations missed during the first half of the year. Also, complementary observations can be made in the second day that, when paired with results from the first day, form a stereo map. Although only midway through the orbital operations phase of the mission, MESSENGER had, at the end of the first Mercury solar day, already viewed the entire surface of the planet once and

  3. Spatiotemporal dynamics of phosphorylation in lipid second messenger signaling.

    PubMed

    Antal, Corina E; Newton, Alexandra C

    2013-12-01

    The plasma membrane serves as a dynamic interface that relays information received at the cell surface into the cell. Lipid second messengers coordinate signaling on this platform by recruiting and activating kinases and phosphatases. Specifically, diacylglycerol and phosphatidylinositol 3,4,5-trisphosphate activate protein kinase C and Akt, respectively, which then phosphorylate target proteins to transduce downstream signaling. This review addresses how the spatiotemporal dynamics of protein kinase C and Akt signaling can be monitored using genetically encoded reporters and provides information on how the coordination of signaling at protein scaffolds or membrane microdomains affords fidelity and specificity in phosphorylation events. PMID:23788531

  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. Proteins encoded near the adenovirus late messenger RNA leader segments

    SciTech Connect

    Lewis, J.B.; Anderson, C.W.

    1983-01-01

    Small fragments of adenovirus 2 DNA cloned into the single-strand phage M13 were used to select adenoviral messenger RNAs transcribed from the R-strand between map positions 16 and 30. Cell-free translation of these mRNAs produced proteins of 13.5K, 13.6K, and 11.5K, respectively encoded between the first and second segments of the tripartite major late leader, within the ''i''-leader segment, and immediately preceding the third leader segment. Partial sequence analysis of the 13.6K protein is consistent with the hypothesis that it is encoded within the i-leader segment.

  6. 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

  7. 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.

  8. 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.

  9. MESSENGER observations of multiscale Kelvin-Helmholtz vortices at Mercury

    NASA Astrophysics Data System (ADS)

    Gershman, Daniel J.; Raines, Jim M.; Slavin, James A.; Zurbuchen, Thomas H.; Sundberg, Torbjörn; Boardsen, Scott A.; Anderson, Brian J.; Korth, Haje; Solomon, Sean C.

    2015-06-01

    Observations by the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft in Mercury's magnetotail demonstrate for the first time that Na+ ions exert a dynamic influence on Mercury's magnetospheric system. Na+ ions are shown to contribute up to ~30% of the ion thermal pressure required to achieve pressure balance in the premidnight plasma sheet. High concentrations of planetary ions should lead to Na+ dominance of the plasma mass density in these regions. On orbits with northward-oriented interplanetary magnetic field and high (i.e., >1 cm-3) Na+ concentrations, MESSENGER has often recorded magnetic field fluctuations near the Na+ gyrofrequency associated with the Kelvin-Helmholtz (K-H) instability. These nightside K-H vortices are characteristically different from those observed on Mercury's dayside that have a nearly constant wave frequency of ~0.025 Hz. Collectively, these observations suggest that large spatial gradients in the hot planetary ion population at Mercury may result in a transition from a fluid description to a kinetic description of vortex formation across the dusk terminator, providing the first set of truly multiscale observations of the K-H instability at any of the diverse magnetospheric environments explored in the solar system.

  10. First observations of Mercury's plasma mantle by MESSENGER

    NASA Astrophysics Data System (ADS)

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

    2015-11-01

    We present the first observations of Mercury's plasma mantle, a primary region for solar wind entry into the planetary magnetosphere, located in the high-latitude magnetotail. MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) observations from two orbits on 10 November 2012 have been analyzed. The main plasma mantle features are (1) a steady decrease in proton density as MESSENGER moved deeper into the magnetotail; (2) frequent flux transfer events throughout the magnetosheath and into the magnetotail, suggesting that these events are the primary source for solar wind plasma injection; (3) a diamagnetic depression, due to the presence of plasma, as pressure balance is maintained; and (4) a clear proton velocity dispersion, resulting from lower-energy protons being transported deep into the magnetosphere as higher-energy protons escape downtail. From these velocity dispersions we infer cross-magnetosphere electric potentials of 23 kV and 29 kV, consistent with estimates determined from measurements of magnetopause reconnection rate and tail loading and unloading events.

  11. Translation of globin messenger RNA by the mouse ovum

    PubMed Central

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

    2016-01-01

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

  12. 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.

  13. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2016-02-01

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

  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. 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

  17. 30 CFR 77.704-11 - Use of grounded messenger wires; ungrounded systems.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... AREAS OF UNDERGROUND COAL MINES Grounding § 77.704-11 Use of grounded messenger wires; ungrounded systems. Solely for purposes of grounding ungrounded high-voltage power systems, grounded messenger wires used to suspend the cables of such systems may be used as a grounding medium....

  18. 30 CFR 77.704-11 - Use of grounded messenger wires; ungrounded systems.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... AREAS OF UNDERGROUND COAL MINES Grounding § 77.704-11 Use of grounded messenger wires; ungrounded systems. Solely for purposes of grounding ungrounded high-voltage power systems, grounded messenger wires used to suspend the cables of such systems may be used as a grounding medium....

  19. 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

  20. 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…

  1. 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…

  2. 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...

  3. Receptors for protons or lipid messengers or both?

    PubMed

    Seuwen, Klaus; Ludwig, Marie-Gabrielle; Wolf, Romain M

    2006-01-01

    The subfamily of G protein-coupled receptors comprising GPR4, OGR1, TDAG8, and G2A was originally characterized as a group of proteins mediating biological responses to the lipid messengers sphingosylphosphorylcholine (SPC), lysophosphatidylcholine (LPC), and psychosine. We challenged this view by reporting that OGR1 and GPR4 sense acidic pH and that this process is not affected by concentrations of SPC or LPC previously reported as agonistic. The original publications describing GPR4, OGR1, and G2A as receptors for LPC or SPC have now been retracted, and the first studies exploring receptors of this family as pH sensors in physiology have appeared. Here we review the status of this field and we confirm that GPR4, OGR1, and TDAG8 should be considered as proton-sensing receptors. Negative regulation of these receptors by high micromolar concentrations of lipids appears not specific in our experiments. PMID:17118800

  4. Cyclic di-AMP: another second messenger enters the fray.

    PubMed

    Corrigan, Rebecca M; Gründling, Angelika

    2013-08-01

    Nucleotide signalling molecules contribute to the regulation of cellular pathways in all forms of life. In recent years, the discovery of new signalling molecules in bacteria and archaea, as well as the elucidation of the pathways they regulate, has brought insights into signalling mechanisms not only in bacterial and archaeal cells but also in eukaryotic host cells. Here, we provide an overview of the synthesis and regulation of cyclic di-AMP (c-di-AMP), one of the latest cyclic nucleotide second messengers to be discovered in bacteria. We also discuss the currently known receptor proteins and pathways that are directly or indirectly controlled by c-di-AMP, the domain structure of the enzymes involved in its production and degradation, and the recognition of c-di-AMP by the eukaryotic host. PMID:23812326

  5. Second messenger networks for accurate growth cone guidance.

    PubMed

    Akiyama, Hiroki; Kamiguchi, Hiroyuki

    2015-04-01

    Growth cones are able to navigate over long distances to find their appropriate target by following guidance cues that are often presented to them in the form of an extracellular gradient. These external cues are converted into gradients of specific signaling molecules inside growth cones, while at the same time these internal signals are amplified. The amplified instruction is then used to generate asymmetric changes in the growth cone turning machinery so that one side of the growth cone migrates at a rate faster than the other side, and thus the growth cone turns toward or away from the external cue. This review examines how signal specification and amplification can be achieved inside the growth cone by multiple second messenger signaling pathways activated downstream of guidance cues. These include the calcium ion, cyclic nucleotide, and phosphatidylinositol signaling pathways. PMID:24285606

  6. 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.

  7. Observations of Mercury's Exosphere during the First MESSENGER Flyby

    NASA Astrophysics Data System (ADS)

    Killen, Rosemary M.; McClintock, William E.; Bradley, E. Todd; Izenberg, Noam R.; Lankton, Mark R.; Mouawad, Nelly; Sprague, Ann L.; Vervack, Ronald J., Jr.; Potter, Andrew E.; Bida, Thomas A.

    2008-09-01

    Abstract Observations of Mercury's tenuous exosphere were taken with the UltraViolet and Visible Spectrometer (UVVS) of the Mercury Atmospheric and Surface Composition Spectrometer (MASCS) during MESSENGER's first Mercury flyby on January 14, 2008 [1]. Concurrent ground-based observations of the sodium exospheric emission were taken at the McMath-Pierce Solar Telescope at Kitt Peak, Arizona [2] (Fig. 1). We make some interesting comparisons. In particular, observations of neutral sodium in the antisunward tail region during the flyby [2] are compared with tail observations taken at the McMath- Pierce solar telescope by Potter, Killen, and Mouawad. Only one Na observation was obtained by UVVS on Mercury's dayside, making our groundbased observations important for understanding the Na distribution at the time of the first MESSENGER flyby. In addition, potassium was detected faintly at the McMath-Pierce solar telescope on Kitt Peak during the flyby timeframe but was not detected with the UVVS. This indicates that K emission may have been patchy and or weak during that time period. Of particular interest is the morphology of the sodium exosphere. A possible north/south asymmetry was seen in the sodium tail in both UVVS (Fig. 2) and ground-based observations (not shown here); however, no definitive asymmetry was seen either on the dayside or nightside at that time. Fig. 2 The sodium tail observed by the MESSENGER MASCS instrument on January 14, 2008. A possible north/south asymmetry is present. The appearance of a possible north/south asymmetry in the sodium tail observed with the MASCS instrument may indicate that the portion of exosphere escaping down the tail is a minor part of the dayside exosphere with a different morphology from that of the bulk of the dayside exosphere. Calcium emission observations by UVVS in the near-tail region exhibited a marked dawn/dusk asymmetry (Fig. 3). Ground-based observations of calcium taken with the cross-dispersed echelle

  8. Localization of angiotensinogen messenger RNA in rat aorta.

    PubMed

    Cassis, L A; Lynch, K R; Peach, M J

    1988-06-01

    The distribution of angiotensinogen messenger (mRNA) was determined in the rat aorta. Other investigators have demonstrated the presence of angiotensinogen mRNA in whole rat aorta; however, its precise location in the blood vessel wall has not been defined. When various layers of the vessel wall were separated by dissection or cell dispersion, angiotensinogen mRNA levels were greatest in the periaortic adipose tissue. Angiotensinogen mRNA was present in very small levels in the adventitia, with no detectable levels in the muscle layer. In addition to periaortic adipose tissue, angiotensinogen mRNA was also present in the interscapular brown fat pad of the rat. The high levels of angiotensinogen mRNA in periaortic brown adipose tissue suggests that angiotensin may be synthesized there and responses may exist in this tissue or adjacent sympathetic nerve terminals. PMID:3383369

  9. Hunting Gravitational Waves with Multi-Messenger Counterparts: Australia's Role

    NASA Astrophysics Data System (ADS)

    Howell, E. J.; Rowlinson, A.; Coward, D. M.; Lasky, P. D.; Kaplan, D. L.; Thrane, E.; Rowell, G.; Galloway, D. K.; Yuan, Fang; Dodson, R.; Murphy, T.; Hill, G. C.; Andreoni, I.; Spitler, L.; Horton, A.

    2015-12-01

    The first observations by a worldwide network of advanced interferometric gravitational wave detectors offer a unique opportunity for the astronomical community. At design sensitivity, these facilities will be able to detect coalescing binary neutron stars to distances approaching 400 Mpc, and neutron star-black hole systems to 1 Gpc. Both of these sources are associated with gamma-ray bursts which are known to emit across the entire electromagnetic spectrum. Gravitational wave detections provide the opportunity for `multi-messenger' observations, combining gravitational wave with electromagnetic, cosmic ray, or neutrino observations. This review provides an overview of how Australian astronomical facilities and collaborations with the gravitational wave community can contribute to this new era of discovery, via contemporaneous follow-up observations from the radio to the optical and high energy. We discuss some of the frontier discoveries that will be made possible when this new window to the Universe is opened.

  10. 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.

  11. 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

  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. 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.

  14. 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.

  15. 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

  16. 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

  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. PMID:19407194

  18. Advanced LIGO and Multi-Messenger Transient Searches

    NASA Astrophysics Data System (ADS)

    Shawhan, Peter S.; LIGO Scientific Collaboration, Virgo Collaboration

    2016-01-01

    The first Advanced LIGO observing run, which began in September 2015, is on track to extend the volume*time reach of the gravitational wave (GW) detector network by an order of magnitude by the end of the year. Searches for transient GW signals from compact binary mergers and other possible sources are a central part of the LIGO-Virgo science program. To enhance those searches and to try to place any detected signals into an astronomical context, we have undertaken an extensive program of partnering with observers to enable prompt transient survey correlations and follow-up observations at all wavelengths, from optical and radio telescopes on the ground to astroparticle detectors to space missions including Fermi and Swift. I will summarize the data collected from the first Advanced LIGO observing run, the transient searches being carried out, and the multi-messenger observing effort.

  19. Second messenger-mediated adjustment of bacterial swimming velocity.

    PubMed

    Boehm, Alex; Kaiser, Matthias; Li, Hui; Spangler, Christian; Kasper, Christoph Alexander; Ackermann, Martin; Kaever, Volkhard; Sourjik, Victor; Roth, Volker; Jenal, Urs

    2010-04-01

    Bacteria swim by means of rotating flagella that are powered by ion influx through membrane-spanning motor complexes. Escherichia coli and related species harness a chemosensory and signal transduction machinery that governs the direction of flagellar rotation and allows them to navigate in chemical gradients. Here, we show that Escherichia coli can also fine-tune its swimming speed with the help of a molecular brake (YcgR) that, upon binding of the nucleotide second messenger cyclic di-GMP, interacts with the motor protein MotA to curb flagellar motor output. Swimming velocity is controlled by the synergistic action of at least five signaling proteins that adjust the cellular concentration of cyclic di-GMP. Activation of this network and the resulting deceleration coincide with nutrient depletion and might represent an adaptation to starvation. These experiments demonstrate that bacteria can modulate flagellar motor output and thus swimming velocity in response to environmental cues. PMID:20303158

  20. 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

  1. 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.

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

    PubMed Central

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

    2014-01-01

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

  3. 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.

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

    NASA Astrophysics Data System (ADS)

    De Bonis, Giulia

    2016-07-01

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

  5. MESSENGER Observations of Upstream Whistler Waves in Mercury's Foreshock Region

    NASA Astrophysics Data System (ADS)

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

    2012-12-01

    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 and low plasma beta 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 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. A preliminary study has shown the existence of at least three types of upstream waves: 1) whistler waves at frequencies near 2 Hz, similar to 1-Hz waves at the Earth; 2) waves with frequencies ~ 0.1 Hz, similar to the large-amplitude 30-s waves at the Earth; 3) fluctuations with broad spectral peaks centered at ~ 0.6 Hz. Unlike the Earth's foreshock where the most prominent upstream wave phenomenon is locally generated large-amplitude 30-s waves, the most common foreshock waves are whistler waves generated at the bow shock, with properties similar to the 1-Hz waves in the Earth's foreshock. These "one-Hz" waves are present in both the flyby data and in every orbit of the orbital data we have surveyed. We will discuss their properties, spatial variations, and propagation and occurrence characteristics in this paper.

  6. 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

  7. MESSENGER observations of solar energetic electrons within Mercury's magnetosphere

    NASA Astrophysics Data System (ADS)

    Gershman, Daniel J.; Raines, Jim M.; Slavin, James A.; Zurbuchen, Thomas H.; Anderson, Brian J.; Korth, Haje; Ho, George C.; Boardsen, Scott A.; Cassidy, Timothy A.; Walsh, Brian M.; Solomon, Sean C.

    2015-10-01

    During solar energetic particle (SEP) events, the inner heliosphere is bathed in MeV electrons. Through magnetic reconnection, these relativistic electrons can enter the magnetosphere of Mercury, nearly instantaneously filling the regions of open field lines with precipitating particles. With energies sufficient to penetrate solid aluminum shielding more than 1 mm thick, these electrons were observable by a number of sensors on the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft. Because of its thin shielding, frequent sampling, and continuous temporal coverage, the Fast Imaging Plasma Spectrometer provided by far the most sensitive measurements of MeV electrons of all MESSENGER sensors. Sharp changes in energetic electron flux coincided with topological boundaries in the magnetosphere, including the magnetopause, polar cap, and central plasma sheet. Precipitating electrons with fluxes equal to ~40% of their corresponding upstream levels were measured over the entire polar cap, demonstrating that electron space weathering of Mercury's surface is not limited to the cusp region. We use these distinct precipitation signatures acquired over 33 orbits during 11 SEP events to map the full extent of Mercury's northern polar cap. We confirm a highly asymmetric polar cap, for which the dayside and nightside boundary latitudes range over ~50-70°N and ~30-60°N, respectively. These latitudinal ranges are consistent with average models of Mercury's magnetic field but exhibit a large variability indicative of active dayside and nightside magnetic reconnection processes. Finally, we observed enhanced electron fluxes within the central plasma sheet. Although these particles cannot form a stable ring current around the planet, their motion results in an apparent trapped electron population at low latitudes in the magnetotail.

  8. 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.

  9. 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

  10. 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

  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

    ... UNDER SPECIAL CERTIFICATE OF MESSENGERS, LEARNERS (INCLUDING STUDENT-LEARNERS), AND APPRENTICES Messengers, Learners (Excluding Student-Learners), and Apprentices § 520.404 What must I demonstrate in...

  12. 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

  13. 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

  14. 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

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

    SciTech Connect

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

    2010-02-15

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

  16. 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…

  17. 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…

  18. Multifunctional triblock copolymers for intracellular messenger RNA delivery

    PubMed Central

    Cheng, C.; Convertine, A.J.; Stayton, P.S.; Bryers, J.D.

    2012-01-01

    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. PMID:22784603

  19. 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.

  20. 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.

  1. Second Messenger-Operated Calcium Entry Through TRPC6.

    PubMed

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

    2016-01-01

    Canonical transient receptor potential 6 (TRPC6) proteins assemble into heteromultimeric structures forming non-selective cation channels. In addition, many TRPC6-interacting proteins have been identified like some enzymes, channels, pumps, cytoskeleton-associated proteins, immunophilins, or cholesterol-binding proteins, indicating that TRPC6 are engaged into macromolecular complexes. Depending on the cell type and the experimental conditions used, TRPC6 activity has been reported to be controlled by diverse modalities. For instance, the second messenger diacylglycerol, store-depletion, the plant extract hyperforin or H2O2 have all been shown to trigger the opening of TRPC6 channels. A well-characterized consequence of TRPC6 activation is the elevation of the cytosolic concentration of Ca(2+). This latter response can reflect the entry of Ca(2+) through open TRPC6 channels but it can also be due to the Na(+)/Ca(2+) exchanger (operating in its reverse mode) or voltage-gated Ca(2+) channels (recruited in response to a TRPC6-mediated depolarization). Although TRPC6 controls a diverse array of biological functions in many tissues and cell types, its pathophysiological functions are far from being fully understood. This chapter covers some key features of TRPC6, with a special emphasis on their biological significance in kidney and blood cells. PMID:27161231

  2. 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

  3. 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

  4. 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

  5. Functionalities of expressed messenger RNAs revealed from mutant phenotypes.

    PubMed

    Liao, Ben-Yang; Weng, Meng-Pin

    2016-07-01

    Total messenger RNAs mRNAs that are produced from a given gene under a certain set of conditions include both functional and nonfunctional transcripts. The high prevalence of nonfunctional mRNAs that have been detected in cells has raised questions regarding the functional implications of mRNA expression patterns and divergences. Phenotypes that result from the mutagenesis of protein-coding genes have provided the most straightforward descriptions of gene functions, and such data obtained from model organisms have facilitated investigations of the functionalities of expressed mRNAs. Mutant phenotype data from mouse tissues have revealed various attributes of functional mRNAs, including tissue-specificity, strength of expression, and evolutionary conservation. In addition, the role that mRNA expression evolution plays in driving morphological evolution has been revealed from studies designed to exploit morphological and physiological phenotypes of mouse mutants. Investigations into yeast essential genes (defined by an absence of colony growth after gene deletion) have further described gene regulatory strategies that reduce protein expression noise by mediating the rates of transcription and translation. In addition to the functional significance of expressed mRNAs as described in the abovementioned findings, the functionalities of other type of RNAs (i.e., noncoding RNAs) remain to be characterized with systematic mutations and phenotyping of the DNA regions that encode these RNA molecules. WIREs RNA 2016, 7:416-427. doi: 10.1002/wrna.1329 For further resources related to this article, please visit the WIREs website. PMID:26748449

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

    PubMed Central

    Weng, Lilian; Menczer, Filippo

    2015-01-01

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

  7. 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…

  8. 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.

  9. 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.

  10. 30 CFR 75.705-11 - Use of grounded messenger wires; ungrounded systems.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... OF LABOR COAL MINE SAFETY AND HEALTH MANDATORY SAFETY STANDARDS-UNDERGROUND COAL MINES Grounding § 75.705-11 Use of grounded messenger wires; ungrounded systems. Solely for purposes of grounding... may be used as a grounding medium....

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

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... OF LABOR COAL MINE SAFETY AND HEALTH MANDATORY SAFETY STANDARDS-UNDERGROUND COAL MINES Grounding § 75.705-11 Use of grounded messenger wires; ungrounded systems. Solely for purposes of grounding... may be used as a grounding medium....

  12. Crosstalk between Second Messengers Predicts the Motility of the Growth Cone

    NASA Astrophysics Data System (ADS)

    Kobayashi, Takahiko; Nagase, Fumiaki; Hotta, Kohji; Oka, Kotaro

    2013-11-01

    Axon guidance involves multiple second messenger signal transduction pathways. Although each signal transduction pathway has been characterized, only a few studies have examined crosstalk between these cascades. Here, we applied a simultaneous second messenger imaging method to the growth cone and demonstrated correlations between cAMP, cGMP, and Ca2+. The levels of cAMP and cGMP in non-stimulated freely extending growth cones showed a negative correlation without delay. Although there was no direct correlation between cAMP and Ca2+, examination of cross correlations using small time windows showed frequent switching behavior from negative to positive and vice versa. Furthermore, spatially asymmetric cAMP and cGMP signals in freely deviating growth cones were visualized directly. These results indicate that we succeed in relating second messenger crosstalk to growth cone deviation and extension, and also indicate the possibility of predicting axon guidance from this second messenger crosstalk.

  13. 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.

  14. 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.

  15. 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. PMID:25411927

  16. 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

  17. Mercury's bow shock and foreshock waves observed by Messenger

    NASA Astrophysics Data System (ADS)

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

    2013-09-01

    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. Mercury's bow shock is unique in our solar system as it is produced by moderate Mach number and low plasma beta solar wind blowing over a small magnetized body with a predominately radial interplanetary magnetic field. We use Messenger high resolution (20 samples per second) magnetic field data to study Mercury's bow shock structure, and the characteristics of ultra low frequency waves observed at the foreshock. Bow shock profiles depend on the upstream Mach number, on shock geometry with respect to the upstream magnetic field, and on the plasma beta. Mercury's bow shock is weaker than Earth's with a Mach number MA ˜ 3, and is 10 times smaller. Thus, a more laminar shock is expected and a less complex foreshock may develop. A preliminary study has shown the existence of at least three types of waves: 1) whistler waves at frequencies near 2 Hz; 2) waves with frequencies ~ 0.1 Hz; 3) fluctuations with broad spectral peaks centered at ~ 0.6 Hz. Whistler waves propagate at angles up to 30 degrees, and lower frequency waves are more parallel propagating. We investigate wave properties such as polarization, ellipticity and compressibility. We also discuss wave origin and evolution. While whistler waves may be generated at the bow shock, the origin of lower frequency waves can be attributed to local generation by kinetic ion-ion instabilities. Due to the small scale size of Mercury's foreshock it is possible that waves suffer less steepening than at Earth.

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

    NASA Astrophysics Data System (ADS)

    Sarantos, Menelaos; Killen, Rosemary; McClintock, William; Bradley, E. Todd; Benna, Mehdi; Slavin, James; Solomon, Sean

    2010-05-01

    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 processes 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 source at lower temperatures, 3000-5000 K. The cooler process is consistent with an impact vaporization source at an inferred rate of (3-7)x105 atoms cm-2 s-1. Models of ion sputtering indicate that this process may provide ~20% of the column abundance measured over the polar areas if a mean influx to the surface of 2x108 solar-wind protons cm-2 s-1 poleward of ±50° latitude and an effective sputter yield of 0.1 per ion are assumed. This result leads to the conclusion that another energetic process, such as the rapid photodissociation of exospheric MgO, assumed to be produced by meteoroid and micrometeoroid impacts at an inferred rate of (5-12)x105 molecules cm-2 s-1, is required in order to explain the residual distant neutral component. The total amount of impact-produced magnesium is found to be less than that predicted by impact vaporization models for any reasonable combination of magnesium abundance in the regolith, a result that, subject to uncertainties in the meteoroid influx, suggests that condensation during hypervelocity impacts might constitute a major loss process for gas-phase refractories.

  19. 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.

  20. Mercury’s Sodium Exosphere: Up-Close with MESSENGER

    NASA Astrophysics Data System (ADS)

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

    2013-10-01

    The Mercury Atmospheric and Surface Composition Spectrometer (MASCS) UltraViolet and Visible Spectrometer (UVVS) on the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft orbiting Mercury provides the first up-close look at the planet’s sodium exosphere. We have observed the exosphere from orbit almost daily for more than 9 Mercury years and have used these data to make estimates of sodium density and temperature for the equatorial dayside and south pole. We find that the density varies over time but that this variability repeats itself: the density and temperature at a given local time and true anomaly (time of year) are nearly identical from one Mercury year to the next. The bulk of the exosphere has a temperature of around 1200 K, consistent with photon-stimulated desorption, although a more energetic and as-yet uncertain mechanism populates the relatively tenuous high altitudes and tail. The density varies in a manner consistent with transport caused by radiation pressure, which acts to push sodium away from noon and toward the terminators. Radiation pressure transport is one aspect of the exosphere identified by ground based observers over the last three decades. Some interpretations of their data, however, are inconsistent with our analysis of the orbital data. For example, they conclude that the exosphere has a persistent dawn/dusk asymmetry with more sodium at dawn, while we see a dawn/dusk asymmetry only during half of Mercury’s year. Many ground-based observers also reported frequent brightenings of polar sodium emissions and attributed them to episodic ion flux. Our limited observations of the south polar region show primarily seasonal, rather than episodic, variability.

  1. MESSENGER Observations of the Distribution of Planetary Ions Near Mercury

    NASA Astrophysics Data System (ADS)

    Zurbuchen, T.; Raines, J. M.; Slavin, J. A.; Gershman, D. J.; Gilbert, J. A.; Gloeckler, G.; Anderson, B. J.; Baker, D. N.; Korth, H.; Krimigis, S. M.; Sarantos, M.; Schriver, D.; McNutt, R. L.; Solomon, S. C.

    2011-12-01

    We report global observations of the ionized exosphere of Mercury measured by the Fast Imaging Plasma Spectrometer (FIPS) on MESSENGER during the spacecraft's first months in orbit since March 18, 2011. We observe considerable variability, presumably due to changes in the solar wind and heliospheric magnetic field near Mercury, but some large-scale properties were persistent throughout the observation period. Global maps of heavy ion fluxes at Mercury are clearly peaked in the northern cusp region, pointing to the importance of the polar regions as sources of Mercury's ionized exosphere. On the nightside, plasma is regularly observed near equatorial regions. The observed fluxes of He ions are more evenly distributed, indicating a spatially more uniform source of neutral He in Mercury's environment. The observed ion distributions suggest either rapid energization in the inner magnetosphere, to energies greater than 10 keV within only 0.2 Mercury radii, or that ions energized in the magnetosheath or other regions are transported to lower latitudes. We derive densities and temperatures of key constituents using a model-based technique to account for observation geometry and effects of limited field of view. Although, on average, protons dominate by number density, the pressure of Na ions can exceed that of protons in the cusp and nightside equatorial regions. This initial survey of Mercury's plasma ion environment indicates that the mass loading and thermal pressure effects of the heavier planetary ions, especially the oxygen and sodium groups, will be very important, and perhaps even dominant, in determining magnetospheric structure and dynamics.

  2. Reference surfaces of the planet Mercury from MESSENGER

    NASA Astrophysics Data System (ADS)

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

    2016-01-01

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

  3. 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.

  4. 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.

  5. 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.

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

    NASA Astrophysics Data System (ADS)

    Tosi, Nicola

    2015-04-01

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

  7. 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.

  8. 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

  9. 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

  10. MESSENGER Disappearing Dayside Magnetosphere Events: Evidence for Severe Dayside Erosion and/or Compression?

    NASA Astrophysics Data System (ADS)

    Middleton, H. R.; Slavin, J. A.; Raines, J. M.; Jia, X.; Anderson, B. J.; Mays, M. L.; Zurbuchen, T.

    2014-12-01

    During northward passes over Mercury's dayside hemisphere, the MESSENGER spacecraft normally enters the dayside magnetosphere before it descends to below ~ 500 km altitude. However, for some of these dayside passes the dayside magnetosphere is completely absent in the magnetometer (MAG) and Fast Imaging Plasma Spectrometer (FIPS) observations. During these "disappearing" dayside magnetosphere passes the MESSENGER measurements indicate that the spacecraft passed directly from the magnetosheath into the northern magnetospheric cusp and, finally, the high latitude nightside magnetosphere. Likely causes of these unusual events are severe reconnection-driven erosion and/or solar wind compression of the dayside magnetosphere, to the point where the closed field line dayside magnetosphere lies equatorward and/or below the orbit of MESSENGER. A survey of such cases in the MESSENGER data is presented. The hypothesis that these events are produced by extreme dayside magnetosphere reconnection and/or solar wind compression, is tested using ENLIL predictions of solar wind conditions at Mercury orbit and analysis of the MESSENGER measurements in the cusp and high-latitude nightside magnetosphere.

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

    NASA Astrophysics Data System (ADS)

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

    2011-12-01

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

  12. 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

  13. 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,

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

    NASA Technical Reports Server (NTRS)

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

    2007-01-01

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

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. The regulation of GRP78 and messenger RNA levels by hypoxia is modulated by protein kinase C activators and inhibitors

    SciTech Connect

    Koong, A.C.; Auger, E.A.; Chen, E.Y.; Giaccia, A.J.

    1994-04-01

    In this study, we have shown that steady-state levels of glucose-regulated 78 kDa (GRP78) protein and messenger RNA increase during a 5-h exposure to 0.02% oxygen. This increase in GRP78 protein and mRNA induced by hypoxia can be abolished by a 1-h pretreatment of cells before hypoxia with the protein kinase C (PKC) inhibitors staurosporine and H7 at concentrations at which the drugs themselves do not cause cytotoxicity. Although all studies using protein kinase inhibitors must be interpreted with caution, staurosporine and H7 have been shown to be potent inhibitors of PKC activity, suggesting a role for PKC in mediating the transcriptional regulation of GRP78 by hypoxia. Further support for PKC in regulating GRP78 gene expression by hypoxia stems from gel-mobility shift studies in mixtures of nuclear extracts from aerobic or hypoxic cells with a 36 bp region of the GRP78 promoter (-170 to -135). Binding of this factor could be inhibited by pretreating cells with the PKC inhibitor staurosporine before hypoxia or activated by treating cells with the PKC-activating phorbol ester TPA. These data suggest that activation of this hypoxia-responsive factor is sensitive to oxygen levels and seems to be mediated through a PKC signal transduction pathway. 13 refs., 4 figs.

  20. 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

  1. 29 CFR 520.402 - How do I obtain authority to employ messengers, learners, or apprentices at subminimum wages?

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 29 Labor 3 2012-07-01 2012-07-01 false How do I obtain authority to employ messengers, learners, or apprentices at subminimum wages? 520.402 Section 520.402 Labor Regulations Relating to Labor (Continued) WAGE AND HOUR DIVISION, DEPARTMENT OF LABOR REGULATIONS EMPLOYMENT UNDER SPECIAL CERTIFICATE OF MESSENGERS, LEARNERS...

  2. Selective induction of the glucose-regulated protein grp78 in human monocytes by bacterial extracts (OM-85): a role for calcium as second messenger.

    PubMed

    Jacquier-Sarlin, M R; Dreher, D; Polla, B S

    1996-09-01

    Heat shock/stress proteins (HSP) act as molecular chaperones, protect cells from injury, and are involved in the immune response. We investigated the effects of the immunomodulating bacterial extracts OM-85 on the stress response in normal human peripheral blood monocytes. While OM-85 did not induce the classical HSP, we show here, using 2D gel electrophoresis combined with immunoblotting, the induction of the glucose regulated protein grp78 (the immunoglobulin heavy chain binding protein BiP) along with the described accumulation of pro-interleukin-1 beta. The increased Ca2+ mobilization observed with OM-85 is the likely second messenger for grp78 induction. Recent studies are in favor of a protective role of grp78 against cytokine-mediated cytotoxicity and apoptosis. We suggest that grp78 induction following exposure to OM-85 explains, at least in part, the immunodulatory and protective effects of the bacterial extracts. PMID:8806608

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

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

  4. 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…

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

    ERIC Educational Resources Information Center

    Jones, Phil

    2008-01-01

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

  6. 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.

  7. 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…

  8. Mercury's rotational parameters from MESSENGER image and laser altimeter data: A feasibility study

    NASA Astrophysics Data System (ADS)

    Stark, Alexander; Oberst, Jürgen; Preusker, Frank; Gwinner, Klaus; Peale, Stanton J.; Margot, Jean-Luc; Phillips, Roger J.; Zuber, Maria T.; Solomon, Sean C.

    2015-11-01

    A novel method has been developed to determine the rotational parameters of Mercury from data acquired by the MESSENGER spacecraft. We exploit the complementarity of laser altimeter tracks taken at different rotational phases and rigid stereo terrain models to determine a Mercury rotational model. In particular, we solve for the orientation of the spin axis, the rotation rate, and the amplitude of the forced libration. In this paper, we verify the proposed method and carry out an extensive simulation of MESSENGER data acquisition with assumed rotational parameters. To assess the uncertainty in the rotational parameters we use mission-typical assumptions for spacecraft attitude and position knowledge as well as for small-scale terrain morphology. We find that the orientation of the spin axis and the libration amplitude can be recovered with an accuracy of a few arc seconds from three years of MESSENGER orbital observations. The rotation rate can be determined to within 5 arc seconds per year. The method developed here serves as a framework for the ongoing analysis of data from the MESSENGER spacecraft. The rotational parameters of Mercury hold important constraints on the internal structure and evolution of the planet.

  9. 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…

  10. 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...

  11. 29 CFR 516.30 - Learners, apprentices, messengers, students, or handicapped workers employed under special...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 29 Labor 3 2013-07-01 2013-07-01 false Learners, apprentices, messengers, students, or handicapped workers employed under special certificates as provided in section 14 of the Act. 516.30 Section 516.30 Labor Regulations Relating to Labor (Continued) WAGE AND HOUR DIVISION, DEPARTMENT OF LABOR REGULATIONS RECORDS TO BE KEPT BY EMPLOYERS...

  12. 29 CFR 516.30 - Learners, apprentices, messengers, students, or handicapped workers employed under special...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 29 Labor 3 2014-07-01 2014-07-01 false Learners, apprentices, messengers, students, or handicapped workers employed under special certificates as provided in section 14 of the Act. 516.30 Section 516.30 Labor Regulations Relating to Labor (Continued) WAGE AND HOUR DIVISION, DEPARTMENT OF LABOR REGULATIONS RECORDS TO BE KEPT BY EMPLOYERS...

  13. 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)

  14. 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).

  15. 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…

  16. 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.

  17. 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.

  18. 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

  19. 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.

  20. The Exploration of Mercury by MESSENGER: Looking Ahead to Orbital Observations

    NASA Astrophysics Data System (ADS)

    Solomon, S. C.; McNutt, R. L.; Bedini, P. D.; Anderson, B. J.; Prockter, L. M.; Blewett, D. T.; Evans, L. G.; Gold, R. E.; Krimigis, S. M.; Murchie, S. L.; Nittler, L. R.; Phillips, R. J.; Slavin, J. A.; Zuber, M. T.

    2010-12-01

    NASA's MESSENGER spacecraft flew by Mercury three times in 2008-09 en route to insertion into orbit about the planet in March 2011. The flybys confirmed that the planet's internal magnetic field is dominantly dipolar, with a vector moment closely aligned with the spin axis. MESSENGER detected Mg and Ca+ in Mercury’s exosphere, demonstrated that Mercury's anti-sunward neutral tail contains multiple species, and revealed that exospheric Na, Ca, and Mg vary differently with space and time, 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 profiled numerous impact craters and fault scarps. MESSENGER images provided evidence for widespread volcanism, and candidate sites for volcanic centers were identified. 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 was a focus for volcanic centers, some with evidence of pyroclastic deposits, and widespread contractional and extensional deformation; smooth plains interior and exterior to the basin postdate the basin-forming event. The interior plains of the ˜290-km-diameter Rachmaninoff basin are among the youngest volcanic material on the planet. Mercury surface units are distinguishable by color and composition; smooth plains occupy ˜40% of the surface area, and low-reflectance material occupies ˜15% of the surface area and is primarily seen in deposits excavated by impact. Reflectance spectra show no evidence for FeO in surface silicates, and reflectance and color imaging observations support the view that Mercury's surface material consists dominantly of Fe-poor, Ca-Mg silicates with an admixture of spectrally neutral opaque minerals. In support of the hypothesis that those opaque minerals are Fe

  1. Mercury Conditions for the MESSENGER Mission Simulated in High- Solar-Radiation Vacuum Tests

    NASA Technical Reports Server (NTRS)

    Wong, Wayne A.

    2003-01-01

    The MESSENGER (Mercury Surface, Space Environment, Geochemistry, and Ranging) spacecraft, planned for launch in March 2004, will perform two flybys of Mercury before entering a year-long orbit of the planet in September 2009. The mission will provide opportunities for detailed characterization of the surface, interior, atmosphere, and magnetosphere of the closest planet to the Sun. The NASA Glenn Research Center and the MESSENGER spacecraft integrator, the Johns Hopkins University Applied Physics Laboratory, have partnered under a Space Act Agreement to characterize a variety of critical components and materials under simulated conditions expected near Mercury. Glenn's Vacuum Facility 6, which is equipped with a solar simulator, can simulate the vacuum and high solar radiation anticipated in Mercury orbit. The MESSENGER test hardware includes a variety of materials and components that are being characterized during the Tank 6 vacuum tests, where the hardware will be exposed to up to 11 suns insolation, simulating conditions expected in Mercury orbit. In 2002, ten solar vacuum tests were conducted, including beginning of life, end of life, backside exposure, and solar panel thermal shock cycling tests. Components tested include candidate solar array panels, sensors, thermal shielding materials, and communication devices. As an example, for the solar panel thermal shock cycling test, two candidate solar array panels were suspended on a lift mechanism that lowered the panels into a liquid-nitrogen-cooled box. After reaching -140 C, the panels were then lifted out of the box and exposed to the equivalent of 6 suns (8.1 kilowatts per square meters). After five cold soak/heating cycles were completed successfully, there was no apparent degradation in panel performance. An anticipated 100-hr thermal shield life test is planned for autumn, followed by solar panel flight qualification tests in winter. Glenn's ongoing support to the MESSENGER program has been instrumental in

  2. [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

  3. 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…

  4. 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…

  5. 75 FR 57505 - Dell Products LP, Winston-Salem (WS-1) Division, Including On-Site Leased Workers From Adecco...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-09-21

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF LABOR Employment and Training Administration Dell Products LP, Winston-Salem (WS-1) Division, Including On- Site Leased Workers From Adecco, Spherion, Patriot Staffing, Manpower, Teksystems, APN, ICONMA, Staffing Solutions, South East and OMNI Resources...

  6. 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...

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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

  13. 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

  14. 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

  15. 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

  16. 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. PMID:25595680

  17. Radiative natural SUSY spectrum from deflected AMSB scenario with messenger-matter interactions

    NASA Astrophysics Data System (ADS)

    Wang, Fei; Yang, Jin Min; Zhang, Yang

    2016-04-01

    A radiative natural SUSY spectrum are proposed in the deflected anomaly mediation scenario with general messenger-matter interactions. Due to the contributions from the new interactions, positive slepton masses as well as a large | A t | term can naturally be obtained with either sign of deflection parameter and few messenger species (thus avoid the possible Landau pole problem). In this scenario, in contrast to the ordinary (radiative) natural SUSY scenario with under-abundance of dark matter (DM), the DM can be the mixed bino-higgsino and have the right relic density. The 125 GeV Higgs mass can also be easily obtained in our scenario. The majority of low EW fine tuning points can be covered by the XENON-1T direct detection experiments.

  18. 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.

  19. 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

  20. 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.

  1. Imaging the Surface of Mercury with MESSENGER: Comparisons with Mariner 10.

    NASA Astrophysics Data System (ADS)

    Prockter, L. M.; Murchie, S. L.; Robinson, M. S.; Head, J. W.; Watters, T. R.; Strom, R. G.; Chapman, C. R.; Domingue, D. L.; Solomon, S. C.; Team, T.

    2008-05-01

    The surface of Mercury was imaged in January 2008, for the first time in over three decades, by the Mercury Dual Imaging System (MDIS) on the MESSENGER spacecraft. Over 1200 images of the surface were acquired, at resolutions as high as 100 m/pixel, comparable to the best images acquired by the Mariner 10 spacecraft in the mid-1970s. Mariner 10 imaged approximately 45% of Mercury's surface, and MESSENGER returned images of an additional 21%, so two-thirds of Mercury has now been imaged by spacecraft at regional resolutions or higher. The MDIS instrument consists of a Narrow Angle Camera (NAC) with a 1.5 degree field of view and a Wide Angle Camera (WAC) with a 10.5 degree field of view. The WAC contains 11 filters spanning the range 430 to 1010 nm, as well as a broadband filter centered at 700 nm and used for optical navigation and calibration. These two imagers are mounted on a pivot assembly with a 90 degree range, allowing the instrument to be pointed independently of the other instruments on the spacecraft. MESSENGER passed only 200 km from Mercury's surface during its first flyby, enabling a number of image mosaics to be acquired at high- and regional-resolutions. On approach to the planet, significant portions of the surface seen under high-sun illumination by Mariner 10 were re-imaged by MESSENGER under excellent low- sun viewing conditions. These new images dramatically reveal topography that was invisible in the Mariner 10 data, such as lobate scarps, which now appear to be common across the surface. After the closest approach point of the flyby, the spacecraft crossed the terminator into daylight, returning the first high-resolution image mosaics of Mercury's previously unimaged hemisphere. In addition, 11-color images were obtained providing fresh input to ongoing studies of the style and evolution of Mercury's surface geology.

  2. Defective control of pre–messenger RNA splicing in human disease

    PubMed Central

    Shkreta, Lulzim

    2016-01-01

    Examples of associations between human disease and defects in pre–messenger RNA splicing/alternative splicing are accumulating. Although many alterations are caused by mutations in splicing signals or regulatory sequence elements, recent studies have noted the disruptive impact of mutated generic spliceosome components and splicing regulatory proteins. This review highlights recent progress in our understanding of how the altered splicing function of RNA-binding proteins contributes to myelodysplastic syndromes, cancer, and neuropathologies. PMID:26728853

  3. Radial Evolution of a Magnetic Cloud: MESSENGER, STEREO, and Venus Express Observations

    NASA Astrophysics Data System (ADS)

    Good, S. W.; Forsyth, R. J.; Raines, J. M.; Gershman, D. J.; Slavin, J. A.; Zurbuchen, T. H.

    2015-07-01

    The Solar Orbiter and Solar Probe Plus missions will provide observations of magnetic clouds closer to the Sun than ever before, and it will be good preparation for these missions to make full use of the most recent in situ data sets from the inner heliosphere—namely, those provided by MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) and Venus Express—for magnetic cloud studies. We present observations of the same magnetic cloud made by MESSENGER at Mercury and later by Solar TErrestrial RElations Observatory-B (STEREO-B), while the spacecraft were radially aligned in 2011 November. Few such radial observations of magnetic clouds have been previously reported. Estimates of the solar wind speed at MESSENGER are also presented, calculated through the application of a previously established technique. The cloud's flux rope has been analyzed using force-free fitting; the rope diameter increased from 0.18 to 0.41 AU (corresponding to an {r}{{H}}0.94 dependence on heliocentric distance, rH), and the axial magnetic field strength dropped from 46.0 to 8.7 nT (an {r}{{H}}-1.84 dependence) between the spacecraft, clear indications of an expanding structure. The axial magnetic flux was ˜0.50 nT AU2 at both spacecraft, suggesting that the rope underwent no significant erosion through magnetic reconnection between MESSENGER and STEREO-B. Further, we estimate the change in the cloud's angular width by assuming helicity conservation. It has also been found that the rope axis rotated by 30° between the spacecraft to lie close to the solar equatorial plane at STEREO-B. Such a rotation, if it is a common feature of coronal mass ejection propagation, would have important implications for space weather forecasting.

  4. 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.

  5. The synthesis and stability of cytoplasmic messenger RNA during myoblast differentiation in culture.

    PubMed

    Buckingham, M E; Caput, D; Cohen, A; Whalen, R G; Gros, F

    1974-04-01

    The synthesis of poly(A)-containing cytoplasmic RNA was examined in primary myoblast cultures prepared from skeletal muscle of fetal calves. After a period of cell division, these cells undergo fusion, with concomitant appearance of acetylcholine receptor and subsequent myosin synthesis. In the dividing myoblast there is a high level of messenger RNA synthesis, including a 26S RNA, the size of a putative messenger for the large subunit of myosin. In the transition period prior to fusion, there are quantitative changes in RNA synthesis. At this time, there is a pronounced production of 26S RNA, which diminishes during fusion. The possibility that 26S RNA is accumulated in the dividing myoblast was investigated by chase experiments. At fusion, there is a marked increase in the half-lives of a number of messenger RNA species, including 26 S, which increases from about 10 hr in the dividing cell to a value of more than 50 hr. The identity of the more rapidly turning over 26 S in the myoblasts, compared to that of the 26 S at fusion, was examined in terms of polysomal distribution, migration on gels, and hybridization with complementary DNA for the myosin message. The results of these analyses suggest that the 26S species are identical. Thus, it would appear that in a predetermined cell like the myoblast, the transition to the differentiated state of myotube that is synthesizing muscle specific proteins is effected by the stabilization of messenger already being actively transcribed: terminal differentiation, with respect to myosin synthesis, is preceded by the stabilization of 26S RNA. PMID:4524649

  6. Second Messenger Signaling in Bacillus subtilis: Accumulation of Cyclic di-AMP Inhibits Biofilm Formation

    PubMed Central

    Gundlach, Jan; Rath, Hermann; Herzberg, Christina; Mäder, Ulrike; Stülke, Jörg

    2016-01-01

    The Gram-positive model organism Bacillus subtilis produces the essential second messenger signaling nucleotide cyclic di-AMP. In B. subtilis and other bacteria, c-di-AMP has been implicated in diverse functions such as control of metabolism, cell division and cell wall synthesis, and potassium transport. To enhance our understanding of the multiple functions of this second messenger, we have studied the consequences of c-di-AMP accumulation at a global level by a transcriptome analysis. C-di-AMP accumulation affected the expression of about 700 genes, among them the two major operons required for biofilm formation. The expression of both operons was severely reduced both in the laboratory and a non-domesticated strain upon accumulation of c-di-AMP. In excellent agreement, the corresponding strain was unable to form complex colonies. In B. subtilis, the transcription factor SinR controls the expression of biofilm genes by binding to their promoter regions resulting in transcription repression. Inactivation of the sinR gene restored biofilm formation even at high intracellular c-di-AMP concentrations suggesting that the second messenger acts upstream of SinR in the signal transduction pathway. As c-di-AMP accumulation did not affect the intracellular levels of SinR, we conclude that the nucleotide affects the activity of SinR. PMID:27252699

  7. Second Messenger Signaling in Bacillus subtilis: Accumulation of Cyclic di-AMP Inhibits Biofilm Formation.

    PubMed

    Gundlach, Jan; Rath, Hermann; Herzberg, Christina; Mäder, Ulrike; Stülke, Jörg

    2016-01-01

    The Gram-positive model organism Bacillus subtilis produces the essential second messenger signaling nucleotide cyclic di-AMP. In B. subtilis and other bacteria, c-di-AMP has been implicated in diverse functions such as control of metabolism, cell division and cell wall synthesis, and potassium transport. To enhance our understanding of the multiple functions of this second messenger, we have studied the consequences of c-di-AMP accumulation at a global level by a transcriptome analysis. C-di-AMP accumulation affected the expression of about 700 genes, among them the two major operons required for biofilm formation. The expression of both operons was severely reduced both in the laboratory and a non-domesticated strain upon accumulation of c-di-AMP. In excellent agreement, the corresponding strain was unable to form complex colonies. In B. subtilis, the transcription factor SinR controls the expression of biofilm genes by binding to their promoter regions resulting in transcription repression. Inactivation of the sinR gene restored biofilm formation even at high intracellular c-di-AMP concentrations suggesting that the second messenger acts upstream of SinR in the signal transduction pathway. As c-di-AMP accumulation did not affect the intracellular levels of SinR, we conclude that the nucleotide affects the activity of SinR. PMID:27252699

  8. 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.

  9. Temporally resolved direct delivery of second messengers into cells using nanostraws.

    PubMed

    Xu, Alexander M; Kim, Sally A; Wang, Derek S; Aalipour, Amin; Melosh, Nicholas A

    2016-07-01

    Second messengers are biomolecules with the critical role of conveying information to intracellular targets. They are typically membrane-impermeable and only enter cells through tightly regulated transporters. Current methods for manipulating second messengers in cells require preparation of modified cell lines or significant disruptions in cell function, especially at the cell membrane. Here we demonstrate that 100 nm diameter 'nanostraws' penetrate the cell membrane to directly modulate second messenger concentrations within cells. Nanostraws are hollow vertical nanowires that provide a fluidic conduit into cells to allow time-resolved delivery of the signaling ion Ca(2+) without chemical permeabilization or genetic modification, minimizing cell perturbation. By integrating the nanostraw platform into a microfluidic device, we demonstrate coordinated delivery of Ca(2+) ions into hundreds of cells at the time scale of several seconds with the ability to deliver complex signal patterns, such as oscillations over time. The diffusive nature of nanostraw delivery gives the platform unique versatility, opening the possibility for time-resolved delivery of any freely diffusing molecules. PMID:27292263

  10. 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.

  11. 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.

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

    PubMed

    Lee, Eun-Jin; Groisman, Eduardo A

    2012-06-14

    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. PMID:22699622

  13. Cyclic ADP-ribose is a second messenger in the lipopolysaccharide-stimulated proliferation of human peripheral blood mononuclear cells.

    PubMed Central

    Bruzzone, Santina; De Flora, Antonio; Usai, Cesare; Graeff, Richard; Lee, Hon Cheung

    2003-01-01

    Cyclic ADP-ribose (cADPR), a universal calcium mobilizer from intracellular stores, was recently demonstrated to stimulate proliferation of various cell types. The role of cADPR in a specific process of monocyte- and plasma-mediated activation of T-lymphocytes by lipopolysaccharide (LPS) was addressed using human mononuclear cells from peripheral blood (PBMCs). Incubation of PBMCs with 0.1 microg/ml of LPS for 24 h provided a doubling in the intracellular levels of cADPR as compared with unstimulated PBMCs. The cADPR increase was abolished either by prior removal of monocytes or by pre-incubating a whole PBMC population with a monoclonal antibody against the monocyte marker CD14. The increased concentrations of intracellular cADPR elicited by LPS stimulation were paralleled by significant increases in NAD+ levels and in the activities of ectocellular and membrane-bound fractions of ADP-ribosyl cyclase/cADPR hydrolase activities. A cytosolic ADP-ribosyl cyclase was also detectable in PBMCs and its activity was comparably enhanced by LPS stimulation. This soluble cyclase is distinguished from the membrane-bound cyclase by both substrate and inhibitor sensitivities. LPS-stimulated PBMCs showed 2-3-fold increases of intracellular calcium ([Ca2+]i), and these changes were prevented completely by the cADPR antagonist 8-Br-cADPR and by ryanodine. Both compounds, and the cyclase inhibitor nicotinamide, significantly inhibited the T-lymphocyte proliferation induced by LPS in PBMCs. These results demonstrate that cADPR plays a role of second messenger in the adaptive immune recognition process of LPS-stimulated proliferation of PBMCs. PMID:12852785

  14. 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

  15. Activation of two different receptors mobilizes calcium from distinct stores in Xenopus oocytes

    SciTech Connect

    Shapira, H.; Lupu-Meiri, M.; Gershengorn, M.C.; Oron, Y. )

    1990-06-01

    Acetylcholine (ACh) and thyrotropin-releasing hormone (TRH) utilize inositol 1,4,5-trisphosphate (IP3) as a second messenger and evoke independent depolarizing membrane electrical responses accompanied by characteristic {sup 45}Ca efflux profiles in Xenopus laevis oocytes injected with GH3 pituitary cell mRNA. To determine whether this could be accounted for by mobilization of calcium from functionally separate stores, we measured simultaneously {sup 45}Ca efflux and membrane electrical responses to ACh and TRH in single oocytes. We found that depletion of ACh-sensitive calcium store did not affect the membrane electrical response to TRH and the TRH-evoked {sup 45}Ca efflux. Our data suggest that ACh and TRH mobilize calcium from distinct cellular stores in the oocyte. This is the first demonstration in a single cell of strict subcellular compartmentalization of calcium stores coupled to two different populations of cell membrane receptors that utilize the same second messenger.

  16. Social Mobility and Equality.

    ERIC Educational Resources Information Center

    Miller, S. M.

    Social mobility is generally studied in three different ways: stratum mobility, intergenerational social mobility, and intragenerational or career mobility. This paper deals with the first two types of mobility and more with intergenerational mobility than with stratum mobility. The working hypothesis of both discussions is that, in general, a…

  17. 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.

  18. The MESSENGER Earth Flyby: Results from the Mercury Dual Imaging System

    NASA Astrophysics Data System (ADS)

    Prockter, L. M.; Murchie, S. L.; Hawkins, S. E.; Robinson, M. S.; Shelton, R. G.; Vaughan, R. M.; Solomon, S. C.

    2005-12-01

    The MESSENGER (MErcury Surface, Space ENvironment, Geochemistry, and Ranging) spacecraft was launched from Cape Canaveral Air Force Station, Fla., on 3 August 2004. It returned to Earth for a gravity assist on 2 August 2005, providing an exceptional opportunity for the Science Team to perform instrument calibrations and to test some of the data acquisition sequences that will be used to meet Mercury science goals. The Mercury Dual Imaging System (MDIS), one of seven science instruments on MESSENGER, consists of a wide-angle and a narrow-angle imager that together can map landforms, track variations in surface color, and carry out stereogrammetry. The two imagers are mounted on a pivot platform that enables the instrument to point in a different direction from the spacecraft boresight, allowing great flexibility and increased imaging coverage. During the week prior to the closest approach to Earth, MDIS acquired a number of images of the Moon for radiometric calibration and to test optical navigation sequences that will be used to target planetary flybys. Twenty-four hours before closest approach, images of the Earth were acquired with 11 filters of the wide-angle camera. After MDIS flew over the nightside of the Earth, additional color images centered on South America were obtained at sufficiently high resolution to discriminate small-scale features such as the Amazon River and Lake Titicaca. During its departure from Earth, MDIS acquired a sequence of images taken in three filters every 4 minutes over a period of 24 hours. These images have been assembled into a movie of a crescent Earth that begins as South America slides across the terminator into darkness and continues for one full Earth rotation. This movie and the other images have provided a successful test of the sequences that will be used during the MESSENGER Mercury flybys in 2008 and 2009 and have demonstrated the high quality of the MDIS wide-angle camera.

  19. 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.

  20. 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.

  1. 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.

  2. 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

  3. 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.

  4. Suppressing gravitino thermal production with a temperature-dependent messenger coupling

    NASA Astrophysics Data System (ADS)

    Badziak, Marcin; Dalianis, Ioannis; Lalak, Zygmunt

    2016-02-01

    We show that the constraints on GMSB theories from the gravitino cosmology can be significantly relaxed if the messenger-spurion coupling is temperature dependent. We demonstrate this novel mechanism in a scenario in which this coupling depends on the VEV of an extra singlet field S that interacts with the thermalized plasma which can result in a significantly suppressed gravitino production rate. In such a scenario the relic gravitino abundance is determined by the thermal dynamics of the S field and it is easy to fit the observed dark matter abundance evading the stringent constraints on the reheating temperature, thus making gravitino dark matter consistent with thermal leptogenesis.

  5. Bifurcations in the interplay of messenger RNA, protein and nonprotein coding RNA

    NASA Astrophysics Data System (ADS)

    Zhdanov, Vladimir P.

    2008-07-01

    The interplay of messenger RNA (mRNA), protein, produced via translation of this RNA, and nonprotein coding RNA (ncRNA) may include regulation of the ncRNA production by protein and (i) ncRNA-protein association resulting in suppression of the protein regulatory activity or (ii) ncRNA-mRNA association resulting in degradation of the miRNA-mRNA complex. The kinetic models describing these two scenarios are found to predict bistability provided that protein suppresses the ncRNA formation.

  6. Detection of the Messenger RNA Encoding for the Ferredoxin-Dependent Glutamate Synthase in Maize Leaf

    PubMed Central

    Commere, Bernard; Vidal, Jean; Suzuki, Akira; Gadal, Pierre; Caboche, Michel

    1986-01-01

    Ferredoxin-dependent glutamate synthase (EC 1.4.7.1), glutamate oxoglutarate aminotransferase (glutamate synthase) (GOGAT) messenger RNA was extracted from maize (Zea mays L.) leaves and partially purified through oligo(dT)-cellulose chromatography and ultracentrifugation in a sucrose gradient. mRNA were translated in vitro using a reticulocyte system. The glutamate synthase subunit was characterized by immunoprecipitation with antibodies raised against the rice (Oryza sativa L.) ferredoxin-glutamate synthase. The in vitro synthesized protein and the 145 kilodaltons genuine maize leaf subunit of GOGAT were found to comigrate in sodium dodecyl sulfate-polyacrylamide gel electrophoresis experiments. Images Fig. 1 Fig. 2 Fig. 3 PMID:16664732

  7. 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

  8. 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.

  9. MESSENGER observations of Alfvénic and compressional waves during Mercury's substorms

    NASA Astrophysics Data System (ADS)

    Sun, Wei-Jie; Slavin, James A.; Fu, Suiyan; Raines, Jim M.; Sundberg, Torbjörn; Zong, Qiu-Gang; Jia, Xianzhe; Shi, Quanqi; Shen, Xiaochen; Poh, Gangkai; Pu, Zuyin; Zurbuchen, Thomas H.

    2015-08-01

    MErcury Surface, Space ENviroment, GEochemistry, and Ranging (MESSENGER) magnetic field measurements during the substorm expansion phase in Mercury's magnetotail have been examined for evidence of low-frequency plasma waves, e.g., Pi2-like pulsations. It has been revealed that the By fluctuations accompanying substorm dipolarizations are consistent with pulses of field-aligned currents near the high-latitude edge of the plasma sheet. Detailed analysis of the By fluctuations reveals that they are near circularly polarized electromagnetic waves, most likely Alfvén waves. Soon afterward the plasma sheet thickened and MESSENGER detected a series of compressional waves. These Alfvénic and compressional waves have similar durations (10-20 s), suggesting that they may arise from the same source. Drawing on Pi2 pulsation models developed for Earth, we suggest that the Alfvénic and compressional waves reported here at Mercury may be generated by the quasi-periodic sunward flow bursts in Mercury's plasma sheet. But because they are observed during the period with rapid magnetic field reconfiguration, we cannot fully exclude the possibility of standing Alfvén wave.

  10. Reactive oxygen species and α,β-unsaturated aldehydes as second messengers in signal transduction

    PubMed Central

    Forman, Henry Jay

    2014-01-01

    Signaling by H2O2, α,β-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 H2O2 and HNE. Nonetheless, as H2O2 and HNE are rapidly metabolized in vivo, spatial considerations are extremely important in their actions. Therefore, the locations of sources of H2O2 and α,β-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 H2O2 illustrates these principles. PMID:20716281

  11. 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.

  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. 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.

  14. Testing and validation of orbital operations plans for the MESSENGER mission

    NASA Astrophysics Data System (ADS)

    Berman, Alice F.; Domingue, Deborah L.; Holdridge, Mark E.; Choo, Teck H.; Steele, R. Joshua; Shelton, Richard G.

    2010-07-01

    Launched in 2004, the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft continues on its journey to become, in 2011, the first spacecraft to orbit the planet Mercury. The goal of MESSENGER's one-year orbital mission is to answer several key questions about the structure and history of Mercury and its environment. The science and mission operations teams are testing a concept of operations to use the instrument payload most efficiently and to achieve full mission success. To ensure that all essential observations are obtained and to allow for contingencies, an advance science planning (ASP) effort will develop the full yearlong mission baseline plan prior to orbit insertion. To ensure that the plan can be adapted in response to unexpected events over time, an adjusted baseline plan will be regenerated in the ASP process every five weeks during the actual orbital mission. The near-term science planning (NTSP) activity converts weeklong portions of the baseline plan into executable commands to conduct the orchestrated observations. A feedback process from NTSP to ASP will be used to ensure that the baseline observing plan accounts for and reschedules any unsuccessful observations. A testing and validation plan has been developed for the processes and software that underlie both advance and near-term science planning.

  15. Antisense-induced messenger depletion corrects a COL6A2 dominant mutation in Ullrich myopathy.

    PubMed

    Gualandi, Francesca; Manzati, Elisa; Sabatelli, Patrizia; Passarelli, Chiara; Bovolenta, Matteo; Pellegrini, Camilla; Perrone, Daniela; Squarzoni, Stefano; Pegoraro, Elena; Bonaldo, Paolo; Ferlini, Alessandra

    2012-12-01

    Collagen VI gene mutations cause Ullrich and Bethlem muscular dystrophies. Pathogenic mutations frequently have a dominant negative effect, with defects in collagen VI chain secretion and assembly. It is agreed that, conversely, collagen VI haploinsufficiency has no pathological consequences. Thus, RNA-targeting approaches aimed at preferentially inactivating the mutated COL6 messenger may represent a promising therapeutic strategy. By in vitro studies we obtained the preferential depletion of the mutated COL6A2 messenger, by targeting a common single-nucleotide polymorphism (SNP), cistronic with a dominant COL6A2 mutation. We used a 2'-O-methyl phosphorothioate (2'OMePS) antisense oligonucleotide covering the SNP within exon 3, which is out of frame. Exon 3 skipping has the effect of depleting the mutated transcript via RNA nonsense-mediated decay, recovering the correct collagen VI secretion and restoring the ability to form an interconnected microfilament network into the extracellular matrix. This novel RNA modulation approach to correcting dominant mutations may represent a therapeutic strategy potentially applicable to a great variety of mutations and diseases. PMID:22992134

  16. Exosomes as divine messengers: are they the Hermes of modern molecular oncology?

    PubMed

    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

  17. 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

  18. 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.

  19. Towards a refinement of the D-L fault scale relationship for Mercury using MESSENGER topography

    NASA Astrophysics Data System (ADS)

    Di Achille, G.; Popa, C.; Galluzzi, V.; Ferranti, L.; Zusi, M.; Palumbo, P.

    2013-09-01

    Terrestrial faults show that the maximum displacement along the fault plane (D) scales with the plan-view length of the fault (L) [e.g., 1]. Particularly, it has been proposed that the latter relationship can be simplified to a linear relationship D=γ L (1) where γ is a constant depending on the lithology and overall tectonic context [1]. The linear relationship seems to be also applicable for planetary faults [e.g. 2, 3] and it is one of the few tools commonly used for estimating fault shortening and thus the amount of global planetary contraction for Mercury [4-7]. The ratio of D to L (i.e. γ) strongly affects the resulting estimates of shortening, therefore, the accuracy of γ is fundamental for quantitative tectonic studies based on (1). The coverage and resolution of topographic datasets are crucial for calculating γ. Prior to the MESSENGER mission, γ for Mercury's lobate scarps and wrinkle ridges were defined using the topography obtained from Mariner 10 images and radar observations from Arecibo [e.g. 4, 5]. Here we present preliminary results of a refinement of γ based on a survey of compressional tectonic structure throughout 30% of the Mercury's surface using topography derived from MESSENGER data. Our preliminary results suggest that γ values derived and used in previous studies [5-7] were likely overestimated and could have then resulted in a overestimation of fault shortening and global planetary contraction.

  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. 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

  2. Labelling and imaging of single endogenous messenger RNA particles in vivo.

    PubMed

    Spille, Jan-Hendrik; Kubitscheck, Ulrich

    2015-10-15

    RNA molecules carry out widely diverse functions in numerous different physiological processes in living cells. The RNA life cycle from transcription, through the processing of nascent RNA, to the regulatory function of non-coding RNA and cytoplasmic translation of messenger RNA has been studied extensively using biochemical and molecular biology techniques. In this Commentary, we highlight how single molecule imaging and particle tracking can yield further insight into the dynamics of RNA particles in living cells. In the past few years, a variety of bright and photo-stable labelling techniques have been developed to generate sufficient contrast for imaging of single endogenous RNAs in vivo. New imaging modalities allow determination of not only lateral but also axial positions with high precision within the cellular context, and across a wide range of specimen from yeast and bacteria to cultured cells, and even multicellular organisms or live animals. A whole range of methods to locate and track single particles, and to analyze trajectory data are available to yield detailed information about the kinetics of all parts of the RNA life cycle. Although the concepts presented are applicable to all types of RNA, we showcase here the wealth of information gained from in vivo imaging of single particles by discussing studies investigating dynamics of intranuclear trafficking, nuclear pore transport and cytoplasmic transport of endogenous messenger RNA. PMID:26416818

  3. 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

  4. 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

  5. Effects of the foliar-applied protein "Harpin(Ea)" (messenger) on tomatoes infected with Phytophthora infestans.

    PubMed

    Fontanilla, M; Montes, M; De Prado, R

    2005-01-01

    The active ingredient in Messenger, is Harpin(Ea), a naturally occurring protein derived from Erwinia amylovora, a causal agent of fire blight. When Messenger is applied to a plant, the protein Harpin(Ea) binds foliar receptors to it. The receptors recognize the presence of Harpin(Ea), sending a signal that a pathogen is present, actually "tricking" the plant into thinking that it is under attack. This binding process triggers a cascade of responses affecting a global change of gene expressions, stimulating several distinct biochemical pathways within the plant responsible for growth and disease and insect resistance. The objective of this work is to characterize the development of an induced resistance against Phytophthora infestans. No effective treatment is currently available against this pathogenic agent, which causes the loss of complete harvests of different crops. Tomato plants with and without Messenger applications were inoculated with Phytophthora infestans in the same way. In addition, some plants with and without Messenger applications were not inoculated. Inoculated plants were symptomatologically checked for local and systemic symptoms. Evaluations of the number of tomatoes produced, with or without damage, and their growth, were also carried out. Based on the data obtained from the assays, significant changes were observed in the parameters measured due to Messenger treatment. The severe damage of this disease was reduced in the plants which received Messenger applications. These results open up new pathways in the control of diseases like Phytophthora infestans, in which effective means to combat them still do not exist, or these means are harmful to the environment. PMID:16637157

  6. 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

  7. 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

  8. Small Fault Scarps on Mercury Detected in Low-Altitude MESSENGER Images

    NASA Astrophysics Data System (ADS)

    Watters, T. R.; Solomon, S. C.; Daud, K. E.; Banks, M. E.; Selvans, M. M.; Robinson, M. S.; Murchie, S. L.; Chabot, N. L.; Denevi, B. W.; Ernst, C. M.; Chapman, C. R.; Fassett, C.; Klimczak, C.; Byrne, P. K.; Blewett, D. T.

    2014-12-01

    Lowering MESSENGER's periapsis altitude has provided the opportunity to image the surface of Mercury at higher resolution than was possible during the earlier orbital phase of the mission. In images obtained at spatial scales as good as ~3 m/pixel, small thrust-fault scarps have been detected. The small scarps found thus far are less than 10 km in length and have only tens of meters of relief, much smaller than the large lobate scarps that are the dominant contractional tectonic landform on Mercury and have been attributed to cooling and contraction of the planetary interior. The small scarps on Mercury are nonetheless comparable in scale to similar small scarps documented on the Moon. High-resolution MESSENGER images also reveal that the small scarps crosscut small impact craters (<100 m in diameter). Transected small craters <100 m in diameter on the Moon are Copernican (<~800 My) in age, broadly equivalent to the Kuiperian period on Mercury. Their low relief, lack of superposed small craters, and pristine appearance support the inference that these scarps are geologically young, because small landforms on Mercury will not survive for billions of years under steady meteoroid bombardment. Lunar lobate scarps comparable in scale could be less than 50 My old on the basis of estimated rates of infilling of small, shallow graben in the back-scarp terrain. The impact flux on Mercury is estimated to be a factor of ~3 greater than on the Moon, so the rate of degradation of small landforms on Mercury is expected to be comparably greater. In addition to the detection of small, young scarps, MESSENGER is acquiring images of large lobate scarps from low altitudes. Disturbed and crosscut small impact craters (<100 m in diameter) have been found in high-resolution images on the northwest segment of Carnegie Rupes, indicating recent activity on thrust-fault segments associated with older, prominent scarps. The young, small fault scarps and small-diameter craters crosscut by

  9. New Crater Depth Data for Mercury Derived From MESSENGER Flyby 1 Imagery

    NASA Astrophysics Data System (ADS)

    Herman, M. W.; Chappelow, J. E.; Herrick, R. R.

    2008-12-01

    For small (D < 10 km) craters on Mercury, shadow measurements and photoclinometry are the only viable methods for assessing crater rim-floor depth (d) with the Mariner and MESSENGER Flyby data. A limitation of past shadow measurements was the requirement for simple craters that the shadow pass through crater center in order to get a reliable depth estimate. This restriction means that shadow measurements from the Mariner 10 data were taken along the two narrow longitude bands with acceptable sun angles. Recently, Chappelow (LPSC 2008, Abs. #1441) developed a generalized shadow method that allows determination of crater shape and rim-floor depth for any crater with a conic section of revolution. The boundary of the interior shadow defines a portion of an ellipse. The shape of that ellipse and its offset relative to crater center can be used to solve for crater depth and interior shape (cone, ellipse, parabola, hyperbola). The method does not require that the shadow cross the crater center, but it does require that the viewing angle is close enough to nadir that the rim outline is circular. We are using this method with MESSENGER and Mariner data to expand the amount and areal coverage of depth data for small craters, and to determine the interior shapes of those craters. So far we have estimated depths and shapes for 133 craters (1.0 km < D < 8.0 km) in twelve of the frames from MESSENGER Flyby 1 NAC Mosaic #1 (images range from 117 to 150 m/pixel). Mean d/D is 0.17 (sd 0.04) with a range from 0.09 to 0.29. An exponential fit (in km) is d = (0.178±0.08) D0.89±0.04. Pike's previous results with Mariner data (Mercury, UA Press, 165- 273, 1988) show a unity exponent with a d/D ratio of 0.2, and are reasonably consistent with our work. The shapes of the crater interiors are slightly more conical than parabolic. We have observed some spatial clusters of craters with d/D ratios significantly different than the global mean, and we are investigating whether these areas

  10. 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

  11. 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

  12. 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.

  13. Signalling at membrane contact sites: two membranes come together to handle second messengers.

    PubMed

    Levine, Tim P; Patel, Sandip

    2016-04-01

    It is now clear that many intracellular signals result from multiple membrane-bound compartments acting in concert. Membrane contact sites, regions of close apposition between organelles, have emerged as major points of convergence during signalling, as these are places where material is exchanged. The material exchanged can be either water-insoluble molecules such as membrane lipids that are passed directly between organelles, or ions such as Ca(2+). Here we highlight new insights into the role of contacts in signalling by second messengers, including lipid traffic that underpins re-generation of IP3, the regulation of NAADP and store-operated Ca(2+) signals, and possible involvement in cyclic AMP signalling. PMID:26922871

  14. 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.

  15. 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

  16. 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

  17. Modeling the magnetic field of Mercury based on MESSENGER's partially distributed measurements

    NASA Astrophysics Data System (ADS)

    Oliveira, J. S.; Langlais, B.; Pais, M. A.; Amit, H.

    2015-10-01

    We model the magnetic field of Mercury as measured by the MESSENGER spacecraft during the first six Hermean years using a modified method based on the Equivalent Source Dipole (ESD) approach [1]. We analyze models using different data sets. First we analyze models using eighteen sidereal days separately. Because a periodic signal is observed each 3 sidereal days, we also analyze models of each solar day, corresponding to three consecutive sidereal days. Finally we analyze a model that contains all eighteen siderealday measurements together, termed the 6-solar-daymodel. At the timescale of 1 and 6 solar days, no coherent non-axisymmetric feature is recovered by our method, which was designed to recover an arbitrary internal field. We conclude that this provides strong evidence for the large-scale and close-to-axisymmetry structure of the internal magnetic field of Mercury.

  18. Multi-Messenger Astronomy and Astrophysics with Gravitational-Wave Transients

    NASA Astrophysics Data System (ADS)

    Shawhan, Peter

    2010-02-01

    The successful construction and operation of the LIGO, GEO600 and Virgo detectors has not yet been rewarded with the detection of a gravitational-wave signal. Nevertheless, searches for gravitational-wave inspirals and more general burst signals are already providing meaningful constraints on the population and characteristics of sources, and in particular on the astrophysics of events which are observed by other means, such as gamma-ray bursts and soft gamma repeater flares. I will present and interpret the results from searches that have been completed, and then describe the ways in which this effort is currently being extended to include more types of astrophysical events observed with different ``messengers'' and more modes of utilizing the gravitational-wave data. Besides the direct outcomes from these searches in the near term, we are building the capability to extract significant astronomical information from the signals which will be detected by Advanced LIGO and Advanced Virgo in the coming decade. )

  19. 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

  20. 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.

  1. 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.

  2. 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

  3. 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

  4. 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.

  5. 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

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

    PubMed

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

    2016-01-01

    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

  7. 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

  8. 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.

  9. 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.

  10. Kinetic oscillations in the expression of messenger RNA, regulatory protein, and nonprotein coding RNA

    NASA Astrophysics Data System (ADS)

    Zhdanov, Vladimir P.

    2008-06-01

    The interplay of messenger RNA (mRNA), protein, produced via translation of this RNA, and nonprotein coding RNA (ncRNA) may include regulation of the ncRNA production by protein and (i) ncRNA-mRNA association or (ii) ncRNA-protein association resulting in degradation of the corresponding complex. The kinetic models, describing these two scenarios and taking into account that the association of ncRNA with a target occurs after ncRNA conversion from the initial form to the final form (e.g., from a long RNA to microRNA), are found to predict oscillations provided that the rate of ncRNA formation increases with increasing protein population.

  11. Multi-frequency, multi-messenger astrophysics with Swift. The case of blazars

    NASA Astrophysics Data System (ADS)

    Giommi, Paolo

    2015-09-01

    During its first 10 years of orbital operations Swift dedicated approximately 11% of its observing time to blazars, carrying out more than 12,000 observations of ∼1600 different objects, for a total exposure time of over 25 million seconds. In this paper I briefly discuss the impact that Swift is having on blazar multi-frequency and time-domain astrophysics, as well as how it is contributing to the opening of the era of multi-messenger astronomy. Finally, I present some preliminary results from a systematic analysis of a very large number of Swift XRT observations of blazars. All the "science ready" data products that are being generated by this project will be publicly released. Specifically, deconvolved X-ray spectra and best fit spectral parameters will be available through the ASDC "SED builder" tool ("https://tools.asdc.asi.it/SED")

  12. Antidepressants upregulate messenger RNA levels of the neuroprotective enzyme superoxide dismutase (SOD1).

    PubMed Central

    Li, X M; Chlan-Fourney, J; Juorio, A V; Bennett, V L; Shrikhande, S; Bowen, R C

    2000-01-01

    OBJECTIVE: To investigate the effect of amitriptyline, bupropion, doxepin or venlafaxine on the gene expression of the neuroprotective enzyme superoxide dismutase (SOD1) in a catecholamine cell in vitro model. DESIGN: Molecular study of a cultured cell line. INTERVENTIONS: Rat pheochromocytoma (PC12) cells were incubated in 1 and 10 mumol/L of various antidepressant medications for 24 or 48 hours. OUTCOME MEASURES: Northern blot analysis. RESULTS: Amitriptyline up-regulated SOD1 messenger RNA in a time- and dose-dependent manner. The greatest up-regulation was following incubation with 10 mumol/L amitriptyline for 48 hours. The addition of bupropion, doxepin or venlafaxine to PC12 cell cultures also up-regulated SOD1 mRNA. CONCLUSIONS: These findings suggest that some antidepressants have the ability to positively regulate neuroprotective genes. Images Fig. 2 PMID:10721683

  13. Viruses transfer the antiviral second messenger cGAMP between cells.

    PubMed

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

    2015-09-11

    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

  14. MESSENGER: Insights Regarding the Relationship between Mercury's Surface and Its Neutral and Ionized Exosphere

    NASA Astrophysics Data System (ADS)

    Sprague, Ann L.; Vervack, R. J.; Killen, R. M.; McClintock, W. E.; Starr, R. D.; Schriver, D.; Trávnícek, P.; Orlando, T. M.; McClain, J. L.; Grieves, G. A.; Boynton, W. V.; Lawrence, D. J.; MESSENGER Team

    2010-10-01

    Measurements by instruments on MESSENGER during the spacecraft's three Mercury flybys have led to discoveries of previously undetected neutral (Mg) and ionized (Ca+) species in Mercury's neutral and ionized exosphere and mapped these and previously known constituents (Na, Ca) on the anti-sunward side of the planet and over the poles. Also, Neutron Spectrometer measurements have indicated neutron absorption consistent with the presence of some combination of Fe, Ti, Sm, and Gd. Another element with a high neutron cross section is Mn. Manganese-bearing pyroxene has been inferred from modeling of Mercury Atmospheric and Surface Composition Spectrometer (MASCS) spectra of Mercury's surface. The total neutron cross section of Mn-bearing clinopyroxene, for example, (294.2 barns), is comparable to that of ilmenite (284.0 barns), and we suggest it as a possible neutron absorber at Mercury. Some ions and neutrals can be released directly from mineral surfaces by electron-stimulated desorption (ESD). Because cross sections of neutrals can be higher than photon-stimulated desorption (PSD) cross sections and because active electron precipitation on both the day and night side of Mercury can produce ESD of ions, at least part of the ionized exosphere is produced directly from surface materials by ESD. The process does not require photoionization of atoms or molecules. One inference is that model assumptions for ion production and magnetospheric- interactions may need to add ESD as another source. ESD experiments and simulations of electron precipitation on Mercury provide support for this suggestion. More laboratory work is required to quantify known, and to discover other, pathways to ion desorption from Mercury's surface. Searches for resonant fluorescent emissions from atoms, molecules and ions (e.g., Mn and S emission line triplets near 280 and 162 nm, respectively) in Mercury's neutral and ionized exosphere during the orbital phase of the MESSENGER mission are planned.

  15. 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.

  16. 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.

  17. Structures in the Hermean magnetosphere day side for MESSENGER high latitude polar orbits

    NASA Astrophysics Data System (ADS)

    Varela, Jacobo; Pantellini, Filippo; Moncuquet, Michel

    2015-04-01

    The aim of this research is to simulate the interaction of the solar wind with the magnetic field of Mercury and study the magnetosphere structures in the day side of the planet. We reproduce the magnetosphere structures for two MESSENGER orbits with the satellite closest approach located at high latitudes using the open source MHD code AMRVAC in spherical geometry and a multipolar expansion of the Hermean magnetic field (Anderson, B. J. et al, 2012). We made two simulations with realistic solar wind parameters that show different magnetosphere configurations but in both cases there is a plasma stream that links the back of the bow shock with the North Hemisphere of Mercury. The satellite crosses this structure along the trajectory between the magnetopause and the closest approach to the planet. In the simulation the plasma precipitates from the back of the bow shock region where the interplanetary and the Hermean magnetic field reconnect, following the open magnetic lines to the planet surface showing a fast expansion and cooling. The plasma reaches the surrounding of the planet North pole in a region of strong inflow where the density, temperature and plasma pressure rise. If we measure the magnetic field along the satellite trajectory in the simulation, the position of the magnetospheric structure is correlated with a perturbation of the magnetic field that is observed by MESSENGER at almost the same location. The research leading to these results has received funding from the European Commission's Seventh Framework Programme (FP7/2007-2013) under the grant agreement SHOCK (project number 284515).

  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. Laser Altimetry by MESSENGER over Lobate Scarps Reveals the Lithospheric Structure of Mercury

    NASA Astrophysics Data System (ADS)

    Ritzer, J. A.; Johnson, C. L.; Hauck, S. A.; Watters, T. R.; Barnouin, O. S.; Neumann, G. A.; Mazarico, E.; Phillips, R. J.; Solomon, S. C.; Zuber, M. T.

    2011-12-01

    Images from the Mariner 10 flybys of Mercury demonstrated the widespread occurrence of lobate scarps over the ~45% of the surface imaged by that spacecraft. Lobate scarps are linear to arcuate structures that are tens to hundreds of kilometers long, have topographic relief of hundreds of meters to kilometers, and are interpreted as the surface expression of major thrust faults. Flybys of Mercury by the MESSENGER spacecraft confirmed that lobate scarps are the dominant tectonic feature over nearly the entire planet. Ranging to the surface by the Mercury Laser Altimeter (MLA) since MESSENGER's orbit insertion on March 18, 2011, has yielded hundreds of topographic profiles, largely over Mercury's northern hemisphere. We utilize MLA measurements of lobate scarp topography to constrain fault models and mechanical properties of Mercury's lithosphere. Mean along-track resolution of the MLA data is approximately 300 m, but cross-track spacing varies with latitude, so we currently confine our analyses to individual profiles. Overlaying MLA profiles on images taken by the Mercury Dual Imaging System (MDIS) allows the relief and morphology of lobate surface scarps in Mercury's northern hemisphere to be characterized. Many of these features display the expected signature for lithospheric flexure in response to bending moments applied at underlying thrust faults. We model these faults and their accompanying flexure by means of a mechanical model of the lithosphere that includes an elastic plate overlying an inviscid substrate to accommodate buoyancy forces. Model parameters that are varied are the geometry of the fault and the thickness of the effective elastic lithosphere. Long-wavelength pre-scarp topography is estimated by first de-trending the profiles. We estimate the thickness of the mechanical lithosphere via the relationship between bending moment and plate curvature given a yield strength envelope for Mercury's lithosphere. Comparison of model profiles to the MLA

  20. 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.

  1. 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

  2. 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.

  3. 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…

  4. 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…

  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. 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…

  7. 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…

  8. 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…

  9. 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.

  10. 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

  11. 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

  12. 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.

  13. 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.

  14. 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…

  15. 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

  16. Abundance of Iron on Mercury's Surface from MESSENGER X-Ray Spectrometer Data

    NASA Astrophysics Data System (ADS)

    Weider, S. Z.; Nittler, L. R.; Starr, R. D.; Evans, L. G.; McCoy, T. J.; Solomon, S. C.

    2012-12-01

    Early orbital results from the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) X-Ray Spectrometer (XRS) revealed that Mercury's surface has a low Fe content. The reported Fe/Si ratios (~0.03 to 0.15) gave an upper limit of ~4 wt% Fe. This limit is consistent with the bulk estimate provided by the Gamma-Ray Spectrometer (Fe/Si: ~0.12) and the upper limit of ~6 wt % FeO in silicate minerals that is constrained by reflectance spectroscopy. Reliable Fe abundance estimates are difficult to obtain from XRS data for several reasons, including: (i) strong solar flares are required to excite Fe X-ray fluorescence, and such flares occur rarely; and (ii) energetic particle events often accompany the strongest solar flares, causing fluorescence of the instrument's Cu collimators and spectral contamination close to the Fe K lines at 6.4-7 keV. Forward modeling of XRS data from more than 30 flares during the first year of MESSENGER's orbit reveal that Fe is ubiquitously lower on Mercury (Fe/Si ranging from 0.02 to 0.18, with a peak in the distribution at ~0.06, or ~1.5 wt% Fe) than on other terrestrial planets. Although the abundance of Mg across the surface of Mercury is known to vary according to geological terrain, our data indicate that this variation is not a result of Fe substitution for Mg in mafic silicates. A correlation between Ca and S (and to a lesser extent between Mg and S) has previously been reported from the XRS data. Mercury's high S contents likely reflect the presence of abundant sulfide minerals, such as oldhamite (Ca,Mg,Fe)S. Our data reveal further correlations between Fe and Ca, and between Fe and Mg, suggesting that sulfides (most likely troilite, FeS, and/or oldhamite) are a major carrier of Fe on Mercury's surface. The low Fe content of Mercury's surface supports the very low FeO contents that are predicted from both melting experiments on enstatite chondrites and from thermodynamic modeling. However, even the few wt% Fe on

  17. Structure and dynamics of Mercury's magnetospheric cusp: MESSENGER measurements of protons and planetary ions

    NASA Astrophysics Data System (ADS)

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

    2014-08-01

    The MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft has observed the northern magnetospheric cusp of Mercury regularly since the probe was inserted into orbit about the innermost planet in March 2011. Observations from the Fast Imaging Plasma Spectrometer (FIPS) made at altitudes < 400 km in the planet's cusp have shown average proton densities (>10 cm-3) that are exceeded only by those observed in the magnetosheath. These high plasma densities are also associated with strong diamagnetic depressions observed by MESSENGER's Magnetometer. Plasma in the cusp may originate from several sources: (1) Direct inflow from the magnetosheath, (2) locally produced planetary photoions and ions sputtered off the surface from solar wind impact and then accelerated upward, and (3) flow of magnetosheath and magnetospheric plasma accelerated from dayside reconnection X-lines. We surveyed 518 cusp passes by MESSENGER, focusing on the spatial distribution, energy spectra, and pitch-angle distributions of protons and Na+-group ions. Of those, we selected 77 cusp passes during which substantial Na+-group ion populations were present for a more detailed analysis. We find that Mercury's cusp is a highly dynamic region, both in spatial extent and plasma composition and energies. From the three-dimensional plasma distributions observed by FIPS, protons with mean energies of 1 keV were found flowing down into the cusp (i.e., source (1) above). The distribution of pitch angles of these protons showed a depletion in the direction away from the surface, indicating that ions within 40° of the magnetic field direction are in the loss cone, lost to the surface rather than being reflected by the magnetic field. In contrast, Na+-group ions show two distinct behaviors depending on their energy. Low-energy (100-300 eV) ions appear to be streaming out of the cusp, showing pitch-angle distributions with a strong component antiparallel to the magnetic field (away

  18. Assessing the Crustal Stratigraphy of Mercury: Results from MESSENGER Orbital Observations

    NASA Astrophysics Data System (ADS)

    Ernst, C. M.; Murchie, S. L.; Barnouin, O. S.; Chabot, N. L.; Denevi, B. W.; Head, J. W.; Klimczak, C.; Prockter, L. M.; Solomon, S. C.; Watters, T. R.

    2011-12-01

    Mariner 10 and MESSENGER flyby images revealed subtle color variations across Mercury's surface, many of which are associated with impact craters and basins. Impact craters that excavated material spectrally distinct from the surrounding pre-impact surface serve as windows into the subsurface, allowing observations of material at depth that would otherwise remain hidden to remote observations. Previous localized studies of spectrally distinct, excavated material suggested the presence of buried volcanic plains and a heterogeneous crustal stratigraphy and support the important role of volcanism in the evolution of the crust. MESSENGER's Mercury Dual Imaging System (MDIS) has since acquired global color (1 km/pixel) and high-resolution monochrome (250 m/pixel) base maps of the innermost planet, taken under illumination and observation geometries optimized for observing both color and morphology. These base maps, along with detailed targeted observations (up to 80 m/pixel color and 10 m/pixel monochrome), allow detailed co-mapping of geologic and spectral features across Mercury's surface. Such mapping, along with the use of scaling laws and melt-volume calculations to bound the depth of origin of crater ejecta and central peak structures, allows us to investigate many aspects of Mercury's crustal stratigraphy, including, but not limited to, the following topics: (1) The stratigraphy of four of Mercury's younger large basins: Caloris (1550 km in diameter), Rembrandt (720 km), Beethoven (630 km), and Tolstoj (360 km), which have all been flooded by spectrally distinct volcanic plains. Post-flooding craters of varying sizes enable an estimation of the thickness of the volcanic fill and the nature of the pre-flooding basin floor. These measurements will help to constrain models for subsequent compensation, uplift, and deformation; and incorporation of topography and gravity data link basin fill with the broader lithospheric evolution of Mercury. (2) The depth of origin

  19. 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

  20. 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

  1. 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.

  2. Constraints on Solar Coronal Abundances from MESSENGER X-ray Solar Monitor Data

    NASA Astrophysics Data System (ADS)

    Nittler, L.; Starr, R. D.; Schlemm, C., III; McNutt, R. L.; Solomon, S. C.

    2010-12-01

    The chemical composition of the solar corona is fractionated from that of the photosphere, with elements having low first-ionization-potential (FIP <~10 eV) enriched relative to higher-FIP elements. However, the absolute normalization of coronal abundances relative to photospheric ones as well as possible time variation in coronal abundances (e.g., during flares) is a matter of longstanding controversy. Moreover, the effects of a recent downward revision in photospheric C, N, and especially O abundances on coronal composition have not yet been extensively studied. The shape of the soft X-ray spectrum emitted from the coronal plasma depends strongly on chemical composition both through emission lines and free-bound emission contributions to the continuum. The MESSENGER spacecraft, en route to orbit Mercury, includes a Si-PIN detector to monitor the solar X-ray spectrum (~1.5 to 8 keV) as part of an experiment to determine planetary surface composition via X-ray fluorescence. A pinhole and thin Be window in front of the PIN attenuate much of the flux below 2 keV, providing a high dynamic range in measuring the highly variable solar spectrum. The energy resolution of the solar monitor (~600 eV) is not sufficient to resolve individual solar lines but does allow line complexes of Ca and Fe to be distinguished from continuum during flares. In preparation for analysis of X-ray data from Mercury’s surface, we have begun a systematic effort to fit theoretical solar spectra to MESSENGER solar monitor data, using the CHIANTI 5.2 code and assuming isothermal plasma. The key fitting parameters are the plasma temperature, emission measure, and level of fractionation for low-FIP elements. Preliminary fitting of some 1400 individual spectra (300-450 s integration) from ~200 B-level and above solar flares during June-August 2010 reveals two interesting results: (1) The best fits are obtained for plasma with low-FIP elements enriched by a factor of ~2 relative to photospheric

  3. 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

  4. 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

  5. Extent, age, and resurfacing history of the northern smooth plains on Mercury from MESSENGER observations

    NASA Astrophysics Data System (ADS)

    Ostrach, Lillian R.; Robinson, Mark S.; Whitten, Jennifer L.; Fassett, Caleb I.; Strom, Robert G.; Head, James W.; Solomon, Sean C.

    2015-04-01

    MESSENGER orbital images show that the north polar region of Mercury contains smooth plains that occupy ~7% of the planetary surface area. Within the northern smooth plains (NSP) we identify two crater populations, those superposed on the NSP ("post-plains") and those partially or entirely embayed ("buried"). The existence of the second of these populations is clear evidence for volcanic resurfacing. The post-plains crater population reveals that the NSP do not exhibit statistically distinguishable subunits on the basis of crater size-frequency distributions, nor do measures of the areal density of impact craters reveal volcanically resurfaced regions within the NSP. These results suggest that the most recent outpouring of volcanic material resurfaced the majority of the region, and that this volcanic flooding emplaced the NSP over a relatively short interval of geologic time, perhaps 100 My or less. Stratigraphic embayment relationships within the buried crater population, including partial crater flooding and the presence of smaller embayed craters within the filled interiors of larger craters and basins, indicate that a minimum of two episodes of volcanic resurfacing occurred. From the inferred rim heights of embayed craters, we estimate the NSP to be regionally 0.7-1.8 km thick, with a minimum volume of volcanic material of 4 × 106 to 107 km3. Because of the uncertainty in the impact flux at Mercury, the absolute model age of the post-plains volcanism could be either ∼3.7 or ∼2.5 Ga, depending on the chronology applied.

  6. 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.

  7. 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).

  8. Direct Fe2+ Sensing by Iron-responsive Messenger RNA·Repressor Complexes Weakens Binding*

    PubMed Central

    Khan, Mateen A.; Walden, William E.; Goss, Dixie J.; Theil, Elizabeth C.

    2009-01-01

    Fe2+ is now shown to weaken binding between ferritin and mitochondrial aconitase messenger RNA noncoding regulatory structures ((iron-responsive element) (IRE)-RNAs) and the regulatory proteins (IRPs), which adds a direct role of iron to regulation that can complement the well known regulatory protein modification and degradative pathways related to iron-induced mRNA translation. We observe that the Kd value increases 17-fold in 5′-untranslated region IRE-RNA·repressor complexes; Fe2+, is studied in the absence of O2. Other metal ions, Mn2+ and Mg2+ have similar effects to Fe2+ but the required Mg2+ concentration is 100 times greater than for Fe2+ or Mn2+. Metal ions also weaken ethidium bromide binding to IRE-RNA with no effect on IRP fluorescence, using Mn2+ as an O2-resistant surrogate for Fe2+, indicating that metal ions bound IRE-RNA but not IRP. Fe2+ decreases IRP repressor complex stability of ferritin IRE-RNA 5–10 times compared with 2–5 times for mitochondrial aconitase IRE-RNA, over the same concentration range, suggesting that differences among IRE-RNA structures contribute to the differences in the iron responses observed in vivo. The results show the IRE-RNA·repressor complex literally responds to Fe2+, selectively for each IRE-mRNA. PMID:19720833

  9. Induction of avidin messenger ribonucleic acid in the chick oviduct by progesterone and other steroids.

    PubMed

    Kunnas, T A; Joensuu, T K; Viitala, K K; Sopanen, P; Tuohimaa, P; Kulomaa, M S

    1992-06-01

    Avidin gene expression was analyzed using an avidin immunoassay and RNA hybridization analysis. To ascertain whether the induction of the avidin gene by progesterone remains specific also during secondary restimulation with diethylstilbestrol, chicks were given different steroid hormones or hormone combinations. Progesterone-specific induction of avidin protein and messenger RNA (mRNA) was 15- to 30-fold over the control even after secondary restimulation with diethylstilbestrol. A functional difference between the progesterone response element and glucocorticoid response element was suggested, since dexamethasone alone did not induce avidin in vivo. In spite of progesterone specificity, a combination of progesterone with other steroids nevertheless generated a synergistic increase in the amount of avidin mRNA. This may indicate that binding of progesterone receptor to the progesterone response element may be important to alter the functional activity of other hormone response elements present on the avidin gene. The time response curve of the avidin mRNA induction by progesterone was also determined. Avidin mRNA was detectable 8 h after progesterone induction, and its amount was maximal after 16-24 h. This would indicate that the avidin gene belongs in the so-called late responder genes, which also include chicken ovalbumin, ovomucoid, and lysozyme genes. PMID:1375902

  10. 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

  11. 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.

  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. Cellular localization of dopamine D2 receptor messenger RNA in the rat trigeminal ganglion.

    PubMed

    Peterfreund, R A; Kosofsky, B E; Fink, J S

    1995-12-01

    The actions of dopamine are mediated by specific, high-affinity, G protein-coupled receptors. Multiple subtypes of dopamine receptors have been characterized, including the D2 subtype (D2R). Cells within the dorsal root and petrosal ganglia of the rat express D2R messenger RNA (mRNA) consistent with D2R expression by primary sensory neurons. We hypothesized that neurons of the trigeminal ganglion express D2R mRNA. Total cellular RNA from rat trigeminal ganglia was analyzed on Northern blots under high stringency conditions. Hybridization of trigeminal ganglion RNA resulted in a signal which comigrated with striatal, pituitary, and hypothalamic D2R mRNA. To determine the distribution of D2R expressing cells in the trigeminal ganglion, cryostat sections were analyzed by in situ hybridization followed by emulsion autoradiography. We identified a population of clustered cells labeled with dense grain concentrations over their cytoplasms. These findings demonstrate the expression of D2 dopamine receptor mRNA in discrete subpopulations of neurons in the rat trigeminal ganglion. Our observations suggest that drugs active at dopamine receptors of the D2 subtype are potential modulators of sensory activity of neurons whose cell bodies reside in the trigeminal ganglion. D2 dopamine receptors may thus have a role in clinical pain syndromes involving the head and neck. PMID:7486101

  14. Primary cilium and sonic hedgehog signaling during neural tube patterning: role of GPCRs and second messengers.

    PubMed

    Pal, Kasturi; Mukhopadhyay, Saikat

    2015-04-01

    The ventral neural tube in vertebrates is patterned by a gradient of sonic hedgehog (Shh) secreted from the notochord and floor plate. Forward genetic screens first pointed to the role of the primary cilium in ventral neural tube patterning. Further research has shown that most components of the Shh pathway localize to or shuttle through the primary cilium. In the absence of Shh, the bifunctional Gli transcription factors are proteolytically processed into repressor forms in a protein kinase A (PKA)- and cilium-dependent manner. Recent work suggests that the orphan G-protein-coupled receptor (GPCR) Gpr161 localizes to cilia, and functions as a negative regulator of Shh signaling by determining Gli processing via cAMP signaling. The primary cilium also functions as a signaling compartment for calcium in the Shh pathway. A better understanding of the role of the cilium as a signaling compartment, and the interplay of second messenger systems that regulate PKA activation and Gli amplification during signaling is critical for deciphering the role of Shh during development, neuronal differentiation, and tumorigenesis. PMID:24863049

  15. 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.

  16. Features of Distribution of Mercurian Concentric Basins on the Base of Messenger Data

    NASA Astrophysics Data System (ADS)

    Rodionova, Zhanna; Blue, Jennifer

    MESSENGER images were investigated to expose the distribution of concentric basins on the surface of Mercury. We revealed 49 such objects with outer diameters from 64 km to 488 km, some of which have been formally named (e.g., Bach (214 km), Homer (319 km), Rachmaninov (306 km), Renoir (220 km), Chekhov (194 km), etc.). Fourteen concentric basins are unnamed. Concentric basins share the following common features: the diameter of the outer ridge is twice that of the inner ridge; the surface of the central depression is covered with a fewer number of craters than the surface between the inner and outer ridges; and chains of small craters and valleys usually surround such concentric basins. A histogram of the distribution of these basin dimensions shows that diameters from 160 km to 170 km and 190 km to 220 km are prevalent for concentric basins. About 70% of all concentric basins on Mercury are located in marginal zones between plains and highlands. We have compiled a map of the distribution of concentric basins on the Mercurian surface. It shows that the frequency of concentric basins in the western hemisphere is three times greater than the frequency in the eastern hemisphere. The comparison of concentric basins on Mercury, Moon and Mars is now complete.

  17. Separation technique for messenger RNAs by use of schizophyllan/poly(A) tail complexation.

    PubMed

    Kimura, Taro; Beppu, Akiko; Sakurai, Kazuo; Shinkai, Seiji

    2005-01-01

    Schizophyllan (SPG) is one of the water soluble beta-1,3-glucans and has a peculiar molecular recognition capability, namely, the single stranded SPG (s-SPG) can form a stoichiometric complex with certain polynucleotides such as poly(C) and poly(A), although it cannot bind poly(G) and poly(dC) at all. In this paper, we prepared an s-SPG-appended column and made an attempt to separate polynucleotides on the bases of this molecular recognition capability. The s-SPG-appended column trapped only such RNAs that could form the complex with s-SPG but eluted other RNAs which did not form the complex. Encouraged by the results in the model system, we extended the s-SPG-appended column into separation of native messenger RNAs (mRNAs) from a RNA mixture (total RNA) obtained from yeast. Since eukaryotic mRNAs have a poly(A) tail with 150-300 bases, we supposed that the tails would be trapped by the s-SPG-appended column. The results indicate that mRNAs were separated from total RNA in good yield and with high purity. It should be emphasized that this is the first device to separate natural mRNAs without using a dA/dT Watson-Crick-type interaction. PMID:15638518

  18. 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.

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

    PubMed Central

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

    2015-01-01

    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. PMID:26507781

  20. 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

  1. 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

  2. Evidence for normal vitamin D receptor messenger ribonucleic acid and genotype in absorptive hypercalciuria.

    PubMed

    Zerwekh, J E; Hughes, M R; Reed, B Y; Breslau, N A; Heller, H J; Lemke, M; Nasonkin, I; Pak, C Y

    1995-10-01

    Absorptive hypercalciuria (a stone-forming condition) is characterized by gut hyperabsorption of calcium, hypercalciuria, and reduced bone density. Inasmuch as these features implicate enhanced calcitriol action in gut and bone, we analyzed the vitamin D receptor (VDR) gene to ascertain whether an abnormality of this gene marks patients with intestinal hyperabsorption of calcium. We have compared the frequency of a restriction fragment length polymorphism (Bsm I) associated with different alleles of the VDR gene in a group of 33 well characterized absorptive hypercalciuric patients and a group of 36 normal race- and age-matched control subjects. There was no difference between the distribution of the VDR alleles in the patient population when compared with the normal population. The coding region of VDR messenger RNA was also normal, as determined by both DNA sequence analysis and chemical mismatch cleavage analysis of copy DNA from 11 index absorptive hypercalciuric patients. On the basis of these results, we propose that the enhanced intestinal calcium absorption invariably seen in absorptive hypercalciuria and attendant symptoms of this disorder are not attributable to mutations of the VDR and are not linked to a common VDR genotype. PMID:7559881

  3. 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.

  4. 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.

  5. 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.

  6. 3' UTR length and messenger ribonucleoprotein composition determine endocleavage efficiencies at termination codons.

    PubMed

    Boehm, Volker; Haberman, Nejc; Ottens, Franziska; Ule, Jernej; Gehring, Niels H

    2014-10-23

    Nonsense-mediated mRNA decay (NMD) degrades different classes of mRNAs, including transcripts with premature termination codons (PTCs). The NMD factor SMG6 initiates degradation of substrate mRNAs by endonucleolytic cleavage. Here, we aim to delineate the cascade of NMD-activating events that culminate in endocleavage. We report that long 3' UTRs elicit SMG6-mediated endonucleolytic degradation. The presence of an exon-junction complex (EJC) within the 3' UTR strongly stimulates endocleavage in a distance-independent manner. The interaction of SMG6 with EJCs is not required for endocleavage. Whereas the core NMD component UPF2 supports endonucleolytic decay of long 3' UTR mRNAs, it is mostly dispensable during EJC-stimulated endocleavage. Using high-throughput sequencing, we map endocleavage positions of different PTC-containing reporter mRNAs and an endogenous NMD substrate to regions directly at and downstream of the termination codon. These results reveal how messenger ribonucleoprotein (mRNP) parameters differentially influence SMG6-executed endonucleolysis and uncover central characteristics of this phenomenon associated with translation termination. PMID:25310981

  7. Report on the Third Symposium "cCMP and cUMP as New Second Messengers".

    PubMed

    Schneider, Erich H; Seifert, Roland

    2015-01-01

    The cyclic pyrimidine nucleotides cytidine 3',5'-cyclic monophosphate (cCMP) and uridine 3',5'-cyclic monophosphate (cUMP) have been unequivocally identified in mammalian cells using the most advanced mass spectrometry methods. On October 10, 2014, leading experts in the field met at the Hannover Medical School, Hannover, Germany, to discuss the latest findings in this emerging field of research. Generators, effectors, biological functions, inactivation mechanisms, and model systems for cCMP and cUMP were discussed. Pseudomonas aeruginosa nucleotidyl cyclase toxin ExoY, effectively producing cUMP, was a central topic of the meeting. cCMP and cUMP fulfill the criteria for second messengers. Future research directions in the field will include the identification of specific effector proteins of cCMP and cUMP, new cCMP- and cUMP-generating bacterial toxins, the analysis of new model organisms such as the zebra fish, and elucidation of the function of other noncanonical cyclic nucleotides such as inosine 3',5'-cyclic monophosphate (cIMP). PMID:25471064

  8. Variations in the abundance of iron on Mercury's surface from MESSENGER X-Ray Spectrometer observations

    NASA Astrophysics Data System (ADS)

    Weider, Shoshana Z.; Nittler, Larry R.; Starr, Richard D.; McCoy, Timothy J.; Solomon, Sean C.

    2014-06-01

    We present measurements of Mercury's surface composition from the analysis of MESSENGER X-Ray Spectrometer data acquired during 55 large solar flares, which each provide a statistically significant detection of Fe X-ray fluorescence. The Fe/Si data display a clear dependence on phase angle, for which the results are empirically corrected. Mercury's surface has a low total abundance of Fe, with a mean Fe/Si ratio of ˜0.06 (equivalent to ˜1.5 wt% Fe). The absolute Fe/Si values are subject to a number of systematic uncertainties, including the phase-angle correction and possible mineral mixing effects. Individual Fe/Si measurements have an intrinsic error of ˜10%. Observed Fe/Si values display small variations (significant at two standard deviations) from the planetary average value across large regions in Mercury's southern hemisphere. Larger differences are observed between measured Fe/Si values from more spatially resolved footprints on volcanic smooth plains deposits in the northern hemisphere and from those in surrounding terrains. Fe is most likely contained as a minor component in sulfide phases (e.g., troilite, niningerite, daubréelite) and as Fe metal, rather than within mafic silicates. Variations in surface reflectance (i.e., differences in overall reflectance and spectral slope) across Mercury are unlikely to be caused by variations in the abundance of Fe.

  9. 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

  10. 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

  11. Viral genome RNA serves as messenger early in the infectious cycle of murine leukemia virus.

    PubMed Central

    Shurtz, R; Dolev, S; Aboud, M; Salzberg, S

    1979-01-01

    When NIH/3T3 mouse fibroblasts were infected with the Moloney strain of murine leukemia virus, part of the viral genome RNA molecules were detected in polyribosomes of the infected cells early in the infectious cycle. The binding appears to be specific, since we could demonstrate the release of viral RNA from polyribosomes with EDTA. Moreover, when infection occurred in the presence of cycloheximide, most viral RNA molecules were detected in the free cytoplasm. Size analysis on polyribosomal viral RNA molecules indicated that two size class molecules, 38S and 23S, are present in polyribosomes at 3 h after infection. Analysis of the polyriboadenylate [poly(rA)] content of viral RNA extracted from infected polyribosomes demonstrated that such molecules bind with greatest abundance at 3 h after infection, as has been detected with total viral RNA. No molecules lacking poly(rA) stretches could be detected in polyribosomes. Furthermore, when a similar analysis was performed on unbound molecules present in the free cytoplasm, identical results were obtained. We conclude that no selection towards poly(rA)-containing viral molecules is evident on binding to polyribosomes. These findings suggest that the incoming viral genome of the Moloney strain of murine leukemia virus may serve as a messenger for the synthesis of one or more virus-specific proteins early after infection of mouse fibroblasts. PMID:117118

  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. 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.

  14. 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

  15. 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.

  16. 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

  17. Coordinate estrogen-regulated instability of serum protein-coding messenger RNAs in Xenopus laevis.

    PubMed

    Pastori, R L; Moskaitis, J E; Buzek, S W; Schoenberg, D R

    1991-04-01

    Estrogen causes the cytoplasmic destabilization of albumin and gamma-fibrinogen mRNA in Xenopus laevis liver. The purpose of the present study was to determine whether mRNA destabilization is a generalized phenomenon in response to estrogen, or whether this process is restricted to a particular class of mRNAs. To address this, we have expanded our bank of serum protein-coding cDNA clones to include transferrin, the second protein of inter-alpha-trypsin inhibitor and clone 12B, for which there is no mammalian homolog. Together with albumin and gamma-fibrinogen, these represent more than 85% of the mRNAs encoding liver secreted proteins. Estrogen administration to male Xenopus or to liver explant cultures causes the generalized disappearance of all of these mRNAs. In contrast, estrogen has no effect on actin, ferritin, or poly(A)-binding protein mRNA, all of which encode intracellular proteins. We have previously demonstrated that albumin mRNA is degraded in both messenger ribonucleoprotein and polysome fractions. Sucrose gradient analysis demonstrates the same pattern for degradation of all other serum protein-coding mRNAs. Estrogen has no effect on the amounts or gradient distribution of actin, ferritin, or poly(A)-binding protein mRNA. We conclude that regulated destabilization of mRNAs encoding secreted proteins is a generalized phenomenon in response to estrogen stimulation of Xenopus liver. PMID:1922078

  18. Redirecting T Cell Specificity Using T Cell Receptor Messenger RNA Electroporation.

    PubMed

    Koh, Sarene; Shimasaki, Noriko; Bertoletti, Antonio

    2016-01-01

    Autologous T lymphocytes genetically modified to express T cell receptors or chimeric antigen receptors have shown great promise in the treatment of several cancers, including melanoma and leukemia. In addition to tumor-associated antigens and tumor-specific neoantigens, tumors expressing viral peptides can also be recognized by specific T cells and are attractive targets for cell therapy. Hepatocellular carcinoma cells often have hepatitis B virus DNA integration and can be targeted by hepatitis B virus-specific T cells. Here, we describe a method to engineer hepatitis B virus-specific T cell receptors in primary human T lymphocytes based on electroporation of hepatitis B virus T cell receptor messenger RNA. This method can be extended to a large scale therapeutic T cell production following current good manufacturing practice compliance and is applicable to the redirection of T lymphocytes with T cell receptors of other virus specificities such as Epstein-Barr virus, cytomegalovirus, and chimeric receptors specific for other antigens expressed on cancer cells. PMID:27236807

  19. 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

  20. 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.

  1. 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.

  2. 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.

  3. 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.

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

    PubMed Central

    Auwerx, J H; Chait, A; Wolfbauer, G; Deeb, S S

    1989-01-01

    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-Ca2+, and cyclic AMP pathways. Exogenous phospholipase C (which releases DAG and inositol 1,4,5-triphosphate), PKC activators (phorbol esters and DAG), Ca2+ 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 extent 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. Images PMID:2548077

  5. Simulating Children's Retrieval Errors in Picture-Naming: A Test of Foygel and Dell's (2000) Semantic/Phonological Model of Speech Production

    ERIC Educational Resources Information Center

    Budd, Mary-Jane; Hanley, J. Richard; Griffiths, Yvonne

    2011-01-01

    This study investigated whether Foygel and Dell's (2000) interactive two-step model of speech production could simulate the number and type of errors made in picture-naming by 68 children of elementary-school age. Results showed that the model provided a satisfactory simulation of the mean error profile of children aged five, six, seven, eight and…

  6. 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

  7. 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

  8. Expression of hemocyanin and digestive enzyme messenger RNAs in the hepatopancreas of the Black Tiger Shrimp Penaeus monodon.

    PubMed

    Lehnert, Sigrid A; Johnson, Samuel E

    2002-10-01

    In order to define the cellular site of synthesis for hemocyanin and digestive enzymes in the decapod hepatopancreas, we studied the expression of messenger ribonucleic acids (RNAs) for these molecules in the epithelium lining hepatopancreas tubules. In situ hybridisation of gene probes for the digestive enzymes amylase, cathepsin-L, cellulase, chitinase-1 and trypsin to tissue sections of the shrimp hepatopancreas confirmed that the F-cells lining tertiary, secondary and primary ducts are the sites of synthesis for digestive enzyme messenger RNA (mRNA). The F-cells also contained mRNA for the hemocyanin gene. This finding raises important questions on the mechanism by which mature hemocyanin accumulates in the shrimp hemolymph. Our in situ hybridisation studies further showed that Penaeus monodon F-cells remain transcriptionally active for digestive enzyme mRNAs during periods of starvation. PMID:12381378

  9. 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

  10. A jack of all trades: the multiple roles of the unique essential second messenger cyclic di-AMP.

    PubMed

    Commichau, Fabian M; Dickmanns, Achim; Gundlach, Jan; Ficner, Ralf; Stülke, Jörg

    2015-07-01

    Second messengers are key components of many signal transduction pathways. In addition to cyclic AMP, ppGpp and cyclic di-GMP, many bacteria use also cyclic di-AMP as a second messenger. This molecule is synthesized by distinct classes of diadenylate cyclases and degraded by phosphodiesterases. The control of the intracellular c-di-AMP pool is very important since both a lack of this molecule and its accumulation can inhibit growth of the bacteria. In many firmicutes, c-di-AMP is essential, making it the only known essential second messenger. Cyclic di-AMP is implicated in a variety of functions in the cell, including cell wall metabolism, potassium homeostasis, DNA repair and the control of gene expression. To understand the molecular mechanisms behind these functions, targets of c-di-AMP have been identified and characterized. Interestingly, c-di-AMP can bind both proteins and RNA molecules. Several proteins that interact with c-di-AMP are required to control the intracellular potassium concentration. In Bacillus subtilis, c-di-AMP also binds a riboswitch that controls the expression of a potassium transporter. Thus, c-di-AMP is the only known second messenger that controls a biological process by interacting with both a protein and the riboswitch that regulates its expression. Moreover, in Listeria monocytogenes c-di-AMP controls the activity of pyruvate carboxylase, an enzyme that is required to replenish the citric acid cycle. Here, we review the components of the c-di-AMP signaling system. PMID:25869574

  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. 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.

  13. A comparison of the ultraviolet to near-infrared spectral properties of Mercury and the Moon as observed by MESSENGER

    NASA Astrophysics Data System (ADS)

    Holsclaw, Gregory M.; McClintock, William E.; Domingue, Deborah L.; Izenberg, Noam R.; Blewett, David T.; Sprague, Ann L.

    2010-09-01

    Measurements of the disk-integrated reflectance spectrum of Mercury and the Moon have been obtained by the MESSENGER spacecraft. A comparison of spectra from the two bodies, spanning the wavelength range 220-1450 nm, shows that the absolute reflectance of Mercury is lower than that of the nearside waxing Moon at the same phase angle with a spectral slope that is less steep at visible and near-infrared wavelengths. We interpret these results and the lack of an absorption feature at a wavelength near 1000 nm as evidence for a Mercury surface composition that is low in ferrous iron within silicates but is higher in the globally averaged abundance of spectrally neutral opaque minerals than the Moon. Similar conclusions have been reached by recent investigations based on observations from both MESSENGER and Mariner 10. There is weak evidence for a phase-reddening effect in Mercury that is slightly larger in magnitude than for the lunar nearside. An apparent absorption in the middle-ultraviolet wavelength range of the Mercury spectrum detected from the first MESSENGER flyby of Mercury is found to persist in subsequent observations from the second flyby. The current model of space weathering on the Moon, which also presumably applies to Mercury, does not provide an explanation for the presence of this ultraviolet absorption.

  14. Solar Wind Forcing at Mercury: Comparison Between MESSENGER Observations and ENLIL Model Results for the Low-Altitude Campaign

    NASA Astrophysics Data System (ADS)

    Baker, D. N.; Dewey, R. M.; Odstrcil, D.

    2014-12-01

    Interpretation of observations from the MESSENGER spacecraft in orbit about Mercury benefit greatly from knowledge of solar wind "forcing" parameters. 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 velocity (V) and density (n), ram pressure (~nV2), cross-magnetosphere electric field (VxB), Alfvén Mach number (MA), and other derived quantities of relevance for solar wind-magnetosphere-exosphere interactions. Such parameters as solar wind dynamic pressure are key for determining the Mercury magnetopause standoff distance, as just one example. The relatively high-time-resolution B-field data from MESSENGER can be used to estimate the strength of the product of the solar wind speed and southward IMF strength (Bs) at Mercury. This 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 Mercury magnetosphere. Such parameters also serve as input to the global magnetohydrodynamic and kinetic magnetosphere models that are used to explore magnetospheric and exospheric processes. Such modeling can help assess near-real-time magnetospheric behavior for MESSENGER (as well as other mission analysis and/or ground-based observational campaigns). This solar-wind forcing knowledge is a crucial continuing step toward bringing heliospheric science expertise to bear on solar-planetary interaction studies.

  15. PMP22 messenger RNA levels in skin biopsies: testing the effectiveness of a Charcot-Marie-Tooth 1A biomarker.

    PubMed

    Nobbio, Lucilla; Visigalli, Davide; Radice, Davide; Fiorina, Elisabetta; Solari, Alessandra; Lauria, Giuseppe; Reilly, Mary M; Santoro, Lucio; Schenone, Angelo; Pareyson, Davide

    2014-06-01

    Charcot-Marie-Tooth disease type 1A (CMT1A) is associated with increased gene dosage for PMP22. Therapeutic approaches are currently aiming at correcting PMP22 over-expression. It is unknown whether PMP22 can be used as a biological marker of disease progression and therapy efficacy. We performed quantitative real-time polymerase chain reaction on skin biopsies of 45 patients with CMT1A, obtained at study entry and after 24-months of treatment either with ascorbic acid or placebo. Data of a subgroup of patients were also compared with matched healthy subjects. Finally, we analysed PMP22 messenger RNA levels in sural nerve biopsies. We did not find significant differences in the levels of any known PMP22 transcripts in treated or untreated patients with CMT1A, thus confirming that ascorbic acid does not impact on the molecular features of CMT1A. Most importantly, we did not observe any correlation between PMP22 messenger RNA levels and the different clinical and electrophysiological outcome measures, underscoring the weakness of PMP22 to mirror the phenotypic variability of patients with CMT1A. We did not find increased PMP22 messenger RNA levels in skin and sural nerve biopsies of patients with CMT1A compared with relative controls. In conclusion, this study shows that ascorbic acid does not impact on PMP22 transcriptional regulation and PMP22 is not a suitable biomarker for CMT1A. PMID:24812204

  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. 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

  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. Comparison of clustering techniques for determining compositional units on Mercury from MESSENGER spectral observations

    NASA Astrophysics Data System (ADS)

    D'Amore, Mario; Helbert, Jorn; Maturilli, Alessandro; Marzo, Giuseppe A.; Roush, Ted L.; Hogan, Robert C.; Izenberg, Noam R.; Sprague, Ann L.; Holsclaw, Gregory M.; Head, James; McClintock, William; Solomon, Sean C.

    The Mercury Atmospheric and Surface Composition Spectrometer (MASCS) obtained spectra of much of the surface of Mercury during the first two MESSENGER flybys of the planet. The resulting dataset is composed of several hundred reflectance spectra that have not yet been corrected for any effect due to observing geometry or to surface material phase curves. Our hypothesis is that the separation of surface signal from other contributions can be efficiently performed by the use of statistical techniques. We adopt principal component and clustering analyses to identify and characterize spectral units along the MASCS ground tracks. In order to extract the spectral shapes of the primary surface components exposed in the surface area an-alyzed, we applied an R-mode factor analysis, aiming to find an eigenvector set that minimizes data covariance. Identification of the different components and their abundances is accom-plished by principal component analysis together with an evaluation of the eigenvectors and eigenvalues of the covariance matrix (also called covariance matrix decomposition). A compar-ison of the results using only the near-infrared (NIR) and visible (VIS) portions of the spectra indicates that the NIR spectral range is carrying less information than the VIS portion. We also find that the eigenvectors are essentially unchanged if the full wavelength range is selected (VIS+NIR) rather than limiting observations to the VIS range. The full-range analysis shows that seven eigenvectors are needed to reconstruct the original spectrum to within the level of variability associated with the observational data. Each spectral eigenvector can be regarded as a representative of a distinct spectral class that varies in spatial abundance along the track. The first eigenvector always displays a strong positive or "red" slope, probably strongly linked to uncorrected effects associated with viewing geometry variations, and all eigenvectors show distinctive spectral signatures

  20. 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.

  1. 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.

  2. Killifish metallothionein messenger RNA expression following temperature perturbation and cadmium exposure

    PubMed Central

    Van Cleef-Toedt, Kathleen A.; Kaplan, Lisa A. E.; Crivello, Joseph F.

    2001-01-01

    Metallothionein (MT), a cysteine-rich metal binding protein, is considered to play an essential role in the regulation of intracellular metals. Induction of MT in mammalian and nonmammalian tissues following heavy metal exposure may serve as a defense mechanism and a biomarker of environmental exposure to chemical stressors such as toxic metals. In this study, MT messenger RNA (mRNA) expression was characterized in male and female nonspawning and spawning killifish (Fundulus heteroclitus) following an 8-day exposure to specific sublethal stressors, which included temperature perturbation (26°C or 10°C) and/or 6 ppb of waterborne cadmium chloride (CdCl2). Hepatic, gill, and intestinal MT mRNA, expressed as copy number per microgram of total RNA, was assessed by reverse transcriptase–polymerase chain reaction and electrochemiluminescence using winter flounder (Pleuronectes americanus) MT complementary DNA primers. Liver, gill, and intestine MT mRNA expression was significantly (P < 0.05) increased in nonspawning killifish exposed to 26°C compared with those exposed to 19°C (control). In addition, a significant (P < 0.05) increase in gill MT mRNA induction was observed in nonspawning killifish exposed to 6 ppb of waterborne CdCl2 compared with controls. The results of this study demonstrate significant MT mRNA induction in nonspawning killifish following short-term exposure to physiological and chemical stressors. Thus, further research may be necessary before the use of killifish MT mRNA induction as a biomarker of environmental chemical stress exposure alone. PMID:11795472

  3. 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).

  4. 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.

  5. 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.

  6. 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

  7. MicroRNA and messenger RNA profiling reveals new biomarkers and mechanisms for RDX induced neurotoxicity

    PubMed Central

    2014-01-01

    Background RDX is a well-known pollutant to induce neurotoxicity. MicroRNAs (miRNA) and messenger RNA (mRNA) profiles are useful tools for toxicogenomics studies. It is worthy to integrate MiRNA and mRNA expression data to understand RDX-induced neurotoxicity. Results Rats were treated with or without RDX for 48 h. Both miRNA and mRNA profiles were conducted using brain tissues. Nine miRNAs were significantly regulated by RDX. Of these, 6 and 3 miRNAs were up- and down-regulated respectively. The putative target genes of RDX-regulated miRNAs were highly nervous system function genes and pathways enriched. Fifteen differentially genes altered by RDX from mRNA profiles were the putative targets of regulated miRNAs. The induction of miR-71, miR-27ab, miR-98, and miR-135a expression by RDX, could reduce the expression of the genes POLE4, C5ORF13, SULF1 and ROCK2, and eventually induce neurotoxicity. Over-expression of miR-27ab, or reduction of the expression of unknown miRNAs by RDX, could up-regulate HMGCR expression and contribute to neurotoxicity. RDX regulated immune and inflammation response miRNAs and genes could contribute to RDX- induced neurotoxicity and other toxicities as well as animal defending reaction response to RDX exposure. Conclusions Our results demonstrate that integrating miRNA and mRNA profiles is valuable to indentify novel biomarkers and molecular mechanisms for RDX-induced neurological disorder and neurotoxicity. PMID:25559034

  8. MESSENGER observations of a flux-transfer-event shower at Mercury

    NASA Astrophysics Data System (ADS)

    Slavin, James A.; Imber, Suzanne M.; Boardsen, Scott A.; DiBraccio, Gina A.; Sundberg, Torbjorn; Sarantos, Menelaos; Nieves-Chinchilla, Teresa; Szabo, Adam; Anderson, Brian J.; Korth, Haje; Zurbuchen, Thomas H.; Raines, Jim M.; Johnson, Catherine L.; Winslow, Reka M.; Killen, Rosemary M.; McNutt, Ralph L., Jr.; Solomon, Sean C.

    2012-10-01

    Analysis of MESSENGER magnetic field observations taken in the southern lobe of Mercury's magnetotail and the adjacent magnetosheath on 11 April 2011 indicates that a total of 163 flux transfer events (FTEs) occurred within a 25 min interval. Each FTE had a duration of ˜2-3 s and was separated in time from the next by ˜8-10 s. A range of values have been reported at Earth, with mean values near ˜1-2 min and ˜8 min, respectively. We term these intervals of quasiperiodic flux transfer events “FTE showers.” The northward and sunward orientation of the interplanetary magnetic field during this shower strongly suggests that the FTEs observed during this event formed just tailward of Mercury's southern magnetic cusp. The point of origin for the shower was confirmed with the Cooling model of FTE motion. Modeling of the individual FTE-type flux ropes in the magnetosheath indicates that these flux ropes had elliptical cross sections, a mean semimajor axis of 0.15 RM (where RM is Mercury's radius, or 2440 km), and a mean axial magnetic flux of 1.25 MWb. The lobe magnetic field was relatively constant until the onset of the FTE shower, but thereafter the field magnitude decreased steadily until the spacecraft crossed the magnetopause. This decrease in magnetic field intensity is frequently observed during FTE showers. Such a decrease may be due to the diamagnetism of the new magnetosheath plasma being injected into the tail by the FTEs.

  9. Integration of the Second Messenger c-di-GMP into the Chemotactic Signaling Pathway

    PubMed Central

    Russell, Matthew H.; Bible, Amber N.; Fang, Xin; Gooding, Jessica R.; Campagna, Shawn R.; Gomelsky, Mark; Alexandre, Gladys

    2013-01-01

    ABSTRACT Elevated intracellular levels of the bacterial second messenger c-di-GMP are known to suppress motility and promote sessility. Bacterial chemotaxis guides motile cells in gradients of attractants and repellents over broad concentration ranges, thus allowing bacteria to quickly adapt to changes in their surroundings. Here, we describe a chemotaxis receptor that enhances, as opposed to suppresses, motility in response to temporary increases in intracellular c-di-GMP. Azospirillum brasilense’s preferred metabolism is adapted to microaerophily, and these motile cells quickly navigate to zones of low oxygen concentration by aerotaxis. We observed that changes in oxygen concentration result in rapid changes in intracellular c-di-GMP levels. The aerotaxis and chemotaxis receptor, Tlp1, binds c-di-GMP via its C-terminal PilZ domain and promotes persistent motility by increasing swimming velocity and decreasing swimming reversal frequency, which helps A. brasilense reach low-oxygen zones. If c-di-GMP levels remain high for extended periods, A. brasilense forms nonmotile clumps or biofilms on abiotic surfaces. These results suggest that association of increased c-di-GMP levels with sessility is correct on a long-term scale, while in the short-term c-di-GMP may actually promote, as opposed to suppress, motility. Our data suggest that sensing c-di-GMP by Tlp1 functions similar to methylation-based adaptation. Numerous chemotaxis receptors contain C-terminal PilZ domains or other sensory domains, suggesting that intracellular c-di-GMP as well as additional stimuli can be used to modulate adaptation of bacterial chemotaxis receptors. PMID:23512960

  10. Differential Regulation of β-1,3-Glucanase Messenger RNAs in Response to Pathogen Infection

    PubMed Central

    Ward, Eric R.; Payne, George B.; Moyer, Mary B.; Williams, Shericca C.; Dincher, Sandra S.; Sharkey, Kevin C.; Beck, James J.; Taylor, Hope T.; Ahl-Goy, Patricia; Meins, Frederick; Ryals, John A.

    1991-01-01

    The acidic, extracellular, glucan endo-1,3-β-glucosidases (EC 3.2.1.39; β-1,3-glucanases), pathogenesis-related proteins-2, -N, and -O (i.e. PR-2, PR-N, and PR-O) were purified from Nicotiana tabacum (tobacco) and their partial amino acid sequences determined. Based on these data, complementary DNA (cDNA) clones encoding the proteins were isolated. Additional cDNAs were isolated that encoded proteins approximately 90% identical with PR-2, PR-N, and PR-O. Although the proteins encoded by these cDNAs have not been identified, their deduced amino acid sequences have slightly basic or neutral calculated isoelectric points, as well as carboxy-terminal extensions. These physical characteristics are shared by the vacuolar form of β-1,3-glucanase and other vacuolar localized analogs of PR proteins, suggesting that the unidentified proteins may be similarly localized. A preliminary evolutionary model that separates the β-1,3-glucanase gene family from tobacco into at least five distinct subfamilies is proposed. The expression of β-1,3-glucanase messenger RNAs (mRNAs) in response to infection by tobacco mosaic virus was examined. Messages for the acidic glucanases were induced similarly to the mRNAs for other PR proteins. However, the basic glucanase showed a different response, suggesting that different isoforms are differentially regulated by tobacco mosaic virus infection at the mRNA level. ImagesFigure 1Figure 5Figure 6 PMID:16668198

  11. 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. PMID:26265469

  12. 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

  13. 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.

  14. 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.

  15. Characterization of messenger ribonucleoprotein particles in dormant sporangiospores of the fungus Mucor racemosus

    SciTech Connect

    Chapman, C.P.

    1986-01-01

    Extracts of sporangiospores of Mucor racemosus contained RNA that readily hybridized with (/sup 3/H)polyuridylic acid. Prior to germination, this RNA was in a form sedimenting at <80S. Within 10 minutes after initiating germination, most of this RNA sedimented with polyribosomes and 80S monoribosomes. Particulate material from spore extracts bound to oligo(dT)-cellulose at high ionic strength and was assumed to contain messenger ribonucleoprotein particles (mRNP's). A portion of the mRNP's was released from the column by lowering the ionic strength. Other portions were eluted stepwise in buffer containing 50% and 90% formamide and in 0.1-N NaOH. Identical elution patterns were observed whether monitoring incorporated /sup 31/P-orthophosphate or L-(/sup 32/S)methionine, absorbance at 280 nm, or hybridization of (/sup 3/H)polyuridylic acid. mRNP's from the first two fractions were analyzed. A bimodal population of particles was detected in sedimentation velocity and sedimentation equilibrium centrifugation. Particles eluted at low ionic strength demonstrated a sedimentation coefficient distribution of 20S-to-80S. Particles eluted in formamide demonstrated a sedimentation coefficient distribution of 20S-to-60S. Particles eluted at low ionic strength displayed two peaks in CsCl centrifugation, with buoyant densities of 1.37 gm/cc and 1.59 gm/cc. Particles eluted in formamide displayed a single peak with a buoyant density of 1.61 gm/cc. Particles eluted at low ionic strength and centrifuged in metrizamide solution formed two bands having buoyant densities of 1.15 gm/cc and 1.30 gm/cc; formamide-eluted particles banded only at the higher density. Mucor 40S ribosomal subunits banded at 1.56 gm/cc and 1.28 gm/cc in CsCl and metrizamide solution respectively.

  16. 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

  17. Solar Flare Element Abundances from the Solar Assembly for X-Rays (SAX) on MESSENGER

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

    X-ray spectra in the range 1.5-8.5 keV have been analyzed for 526 large flares detected with the Solar Assembly for X-rays (SAX) on the Mercury MESSENGER spacecraft between 2007 and 2013. For each flare, the temperature and emission measure of the emitting plasma were determined from the spectrum of the continuum. In addition, with the SAX energy resolution of 0.6 keV (FWHM) at 6 keV, the intensities of the clearly resolved Fe-line complex at 6.7 keV and the Ca-line complex at 3.9 keV were determined, along with those of unresolved line complexes from S, Si, and Ar at lower energies. Comparisons of these line intensities with theoretical spectra allow the abundances of these elements relative to hydrogen to be derived, with uncertainties due to instrument calibration and the unknown temperature distribution of the emitting plasma. While significant deviations are found for the abundances of Fe and Ca from flare to flare, the abundances averaged over all flares are found to be enhanced over photospheric values by factors of 1.66 ± 0.34 (Fe), 3.89 ± 0.76 (Ca), 1.23 ± 0.45 (S), 1.64 ± 0.66 (Si), and 2.48 ± 0.90 (Ar). These factors differ from previous reported values for Fe and Si at least. They suggest a more complex relation of abundance enhancement with the first ionization potential (FIP) of the element than previously considered, with the possibility that fractionation occurs in flares for elements with an FIP of less than ˜7 eV rather than ˜10 eV.

  18. Retinoic acid stimulates interstitial collagenase messenger ribonucleic acid in osteosarcoma cells

    NASA Technical Reports Server (NTRS)

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

    1994-01-01

    The rat osteoblastic osteosarcoma cell line UMR 106-01 secretes interstitial collagenase in response to retinoic acid (RA). The present study demonstrates by Northern blot analysis that RA causes an increase in collagenase messenger RNA (mRNA) at 6 h, which is maximal at 24 h (20.5 times basal) and declines toward basal level by 72 h. This stimulation is dose dependent, with a maximal response at 5 x 10(-7) M RA. Nuclear run-on assays show a greater than 20-fold increase in the rate of collagenase mRNA transcription between 12-24 h after RA treatment. Cycloheximide blocks RA stimulation of collagenase mRNA, demonstrating the need for de novo protein synthesis. RA not only causes an increase in collagenase secretion, but is known to decrease collagen synthesis in UMR 106-01 cells. In this study, the increase in collagenase mRNA is accompanied by a concomitant decrease in the level of alpha 1(I) procollagen mRNA, which is maximal at 24 h (70% decrease), with a return to near-control levels by 72 h. Nuclear run-on assays demonstrated that the decrease in alpha 1 (I) procollagen expression does not have a statistically significant transcriptional component. RA did not statistically decrease the stability of alpha 1 (I) procollagen mRNA (calculated t1/2 = 8.06 +/- 0.30 and 9.01 +/- 0.62 h in the presence and absence of RA, respectively). However, transcription and stability together probably contribute to the major decrease in stable alpha 1 (I) procollagen mRNA observed. Cycloheximide treatment inhibits basal level alpha 1 (I) procollagen mRNA accumulation, demonstrating the need for on-going protein synthesis to maintain basal expression of this gene.

  19. Bacterial Rotary Export ATPases Are Allosterically Regulated by the Nucleotide Second Messenger Cyclic-di-GMP*

    PubMed Central

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

    2015-01-01

    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. PMID:26265469

  20. A Hierarchical Cascade of Second Messengers Regulates Pseudomonas aeruginosa Surface Behaviors

    PubMed Central

    Luo, Yun; Zhao, Kun; Baker, Amy E.; Kuchma, Sherry L.; Coggan, Kimberly A.; Wolfgang, Matthew C.; Wong, Gerard C. L.

    2015-01-01

    ABSTRACT  Biofilms are surface-attached multicellular communities. Using single-cell tracking microscopy, we showed that a pilY1 mutant of Pseudomonas aeruginosa is defective in early biofilm formation. We leveraged the observation that PilY1 protein levels increase on a surface to perform a genetic screen to identify mutants altered in surface-grown expression of this protein. Based on our genetic studies, we found that soon after initiating surface growth, cyclic AMP (cAMP) levels increase, dependent on PilJ, a chemoreceptor-like protein of the Pil-Chp complex, and the type IV pilus (TFP). cAMP and its receptor protein Vfr, together with the FimS-AlgR two-component system (TCS), upregulate the expression of PilY1 upon surface growth. FimS and PilJ interact, suggesting a mechanism by which Pil-Chp can regulate FimS function. The subsequent secretion of PilY1 is dependent on the TFP assembly system; thus, PilY1 is not deployed until the pilus is assembled, allowing an ordered signaling cascade. Cell surface-associated PilY1 in turn signals through the TFP alignment complex PilMNOP and the diguanylate cyclase SadC to activate downstream cyclic di-GMP (c-di-GMP) production, thereby repressing swarming motility. Overall, our data support a model whereby P. aeruginosa senses the surface through the Pil-Chp chemotaxis-like complex, TFP, and PilY1 to regulate cAMP and c-di-GMP production, thereby employing a hierarchical regulatory cascade of second messengers to coordinate its program of surface behaviors. PMID:25626906

  1. Vagal afferents are not necessary for the satiety effect of the gut lipid messenger oleoylethanolamide.

    PubMed

    Azari, Elnaz Karimian; Ramachandran, Deepti; Weibel, Sandra; Arnold, Myrtha; Romano, Adele; Gaetani, Silvana; Langhans, Wolfgang; Mansouri, Abdelhak

    2014-07-15

    The endogenous lipid messenger oleoylethanolamide (OEA) inhibits eating and modulates fat metabolism supposedly through the activation of peroxisome proliferator-activated receptor-α (PPARα) and vagal sensory fibers. We tested in adult male rats whether OEA stimulates fatty acid oxidation (FAO) and ketogenesis and whether it increases plasma levels of the satiating gut peptides glucagon-like peptide-1 (GLP-1) and peptide YY (PYY). We also explored whether OEA still inhibits eating after subdiaphragmatic vagal deafferentation (SDA). We found that intraperitoneally injected OEA (10 mg/kg body wt) reduced (P < 0.05) food intake mainly by increasing meal latency and that this effect was stronger in rats fed a 60% high-fat diet (HFD) than in chow-fed rats. OEA increased (P < 0.05) postprandial plasma nonesterified fatty acids and β-hydroxybutyrate (BHB) in the hepatic portal vein (HPV) and vena cava (VC) 30 min after injection, which was more pronounced in HFD- than in chow-fed rats. OEA also increased the protein expression of the key ketogenetic enzyme, mitochondrial 3-hydroxy-3-methylglutaryl-CoA synthase, in the jejunum of HFD-fed rats, but not in the liver or duodenum of either diet group. Furthermore, OEA decreased GLP-1 and PYY concentrations (P < 0.05) in the HPV and VC 30 min after administration. Finally, OEA reduced food intake in SDA and sham-operated rats similarly. Our findings indicate that neither intact abdominal vagal afferents nor prandial increases in GLP-1 or PMID:24829501

  2. 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.

  3. 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.

  4. Innovative island mobile vet.

    PubMed

    Forster, Dan

    2016-06-11

    One of the UK's first mobile veterinary clinics was recently awarded a Queen's Award for Innovation. Mobile Vet was launched on the Isle of Wight in 2013 by Dan Forster and his wife Kirsty, a veterinary nurse. PMID:27288178

  5. 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.

  6. 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…

  7. 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…

  8. 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

  9. The Effect of Nonhydrostatic Features on the Interpretation of Mercury's Mantle Density from MESSENGER Results

    NASA Astrophysics Data System (ADS)

    Gao, Peter; Stevenson, D. J.

    2012-10-01

    Recent Mercury gravity data obtained from MESSENGER, as reported by Smith et al., (Science, 336, 214-217, 2012) and Earth-based radar measurements of Mercury's libration by Margot et al. (Science, 316, 710-714, 2007) have given an estimated value of Mercury's mantle density of 3.650 ± 0.225 g cm-3. However, this value is too large when compared to surface composition results, and thus have led to the hypothesis that a solid layer of FeS exists below the silicate mantle. In this work, we offer an alternate explanation by invoking the effects of a non-spherical core caused by a degree 2, order 2 nonhydrostatic feature in the mantle on Mercury's Cm/C value (mantle moment of inertia divided by total moment of inertia). Pioneered by Peale (Nature, 262, 265-766, 1976), the method used to calculate Cm/C requires that only the planet's mantle contributes to the difference between the non-polar moments of inertia, B-A; thus, if there is a core contribution, then this method breaks down. We resolve this issue by calculating the value of a coefficient that represents the core-contribution to B-A that would multiply the reported Cm/C value to give the correct one, assuming the core-mantle boundary is an equipotential. As this calculation is linear in the absence of other nonhydrostatic features, the value of the coefficient is independent of the magnitude of the nonhydrostatic effect. Thus, this effect must exist for any nonhydrostatic degree 2, order 2 feature, as opposed to the effects of other nonhydrostatic contributions, such as mantle convection. Resulting coefficient values lie between 0.58-0.81 for reasonable core densities, which correspond to mantle densities between 3 and 3.4 g cm-3, matching that of typical silicate compounds. The value of the coefficient varies by less than 1% for variations in mantle and core densities over reasonable ranges.

  10. Mercury's lithospheric thickness and crustal density, as inferred from MESSENGER observations

    NASA Astrophysics Data System (ADS)

    James, P. B.; Mazarico, E.; Genova, A.; Smith, D. E.; Neumann, G. A.; Solomon, S. C.

    2015-12-01

    The gravity field and topography of Mercury measured by the MESSENGER spacecraft have provided insights into the thickness of the planet's elastic lithosphere, Te. We localized the HgM006 free-air gravity anomaly and gtmes_125v03 shape datasets to search for theoretical elastic thickness solutions that best fit a variety of localized coherence spectra between Bouguer gravity anomaly and topography. We adopted a crustal density of ρcrust =2700 kg m-3 for the Bouguer gravity correction, but density uncertainty did not markedly affect the elastic thickness estimates. A best-fit solution in the northern smooth plains (NSP) gives an elastic thickness of Te =30-60 km at the time of formation of topography for a range of ratios of top to bottom loading from 1 to 5. For a mechanical lithosphere with a thickness of ~2Te and a temperature of 1600 °C at the base, this solution is consistent with a geothermal gradient of 9-18 K km-1. A similar coherence analysis exterior to the NSP produces an elastic thickness estimate of Te =20-50 km, albeit with a poorer fit. Coherence in the northern hemisphere as a whole does not approach zero at any wavelength, because of the presence of variations in crustal thickness that are unassociated with elastic loading. The ratios and correlations of gravity and topography at intermediate wavelengths (harmonic degree l between 30 and 50) also constrain regional crustal densities. We localized gravity and topography with a moving Slepian taper and calculated regionally averaged crustal densities with the approximation ρcrust=Zl/(2πG), where Zl is the localized admittance and G is the gravitational constant. The only regional density estimates greater than 2000 kg m-3 for l=30 correspond to the NSP. Density estimates outside of the NSP were unreasonably low, even for highly porous crust. We attribute these low densities to the confounding effects of crustal thickness variations and Kaula filtering of the gravity dataset at the highest harmonic

  11. 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

  12. 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

  13. Mercury's radius change estimates revisited using high incidence angle MESSENGER data

    NASA Astrophysics Data System (ADS)

    Di Achille, G.; Popa, C.; Massironi, M.; Ferrari, S.; Mazzotta Epifani, E.; Zusi, M.; Cremonese, G.; Palumbo, P.

    2012-04-01

    obtained in the present study are up to five times higher with respect to previous estimates. Our results are more compatible with recent studies suggesting that the Mercury's radius contraction could have been up to 5-6 km throughout its thermal evolution than previous results, supporting the idea that Mercury could have recorded more tectonism than that required to account for 1-2 km of radial contraction. These estimates should be confirmed by further observations over significant portions of the planet and at most favorable sun angle conditions using data from the MESSENGER orbital phase and the high resolution basemaps which will be provided by the next BepiColombo mission.

  14. 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

  15. Human bitter perception correlates with bitter receptor messenger RNA expression in taste cells123

    PubMed Central

    Lipchock, Sarah V; Mennella, Julie A; Spielman, Andrew I; Reed, Danielle R

    2013-01-01

    Background: Alleles of the receptor gene TAS2R38 are responsible in part for the variation in bitter taste perception of 6-n-propylthiouracil (PROP) and structurally similar compounds (eg, glucosinolates in cruciferous vegetables). At low concentrations, people with the PAV (“taster” amino acid sequence) form of TAS2R38 perceive these bitter compounds, whereas most with the AVI (“nontaster” amino acid sequence) form do not; heterozygotes (PAV/AVI) show the widest range of bitter perception. Objectives: The objectives were to examine individual differences in expression of PAV-TAS2R38 messenger RNA (mRNA) among heterozygotes, to test the hypotheses that the abundance of allele-specific gene expression accounts for the variation in human bitter taste perception, and to relate to dietary intake of bitter-tasting beverages and foods. Design: Heterozygous individuals (n = 22) provided psychophysical evaluation of the bitterness of PROP, glucosinolate-containing broccoli juice, non–glucosinolate-containing carrot juice, and several bitter non-TAS2R38 ligands as well as dietary recalls. Fungiform taste papillae were examined for allele-specific TAS2R38 expression by using quantitative polymerase chain reaction. Results: PAV-TAS2R38 mRNA expression was measured in 18 of 22 heterozygous subjects. Relative expression varied widely and positively correlated with ratings of bitterness intensity of PROP (P = 0.007) and broccoli juice (P = 0.004) but not of the control solutions carrot juice (P = 0.26), NaCl (P = 0.68), caffeine (P = 0.24), or urea (P = 0.47). Expression amounts were related to self-reported recent and habitual caffeine intake (P = 0.060, P = 0.005); vegetable intake was too low to analyze. Conclusions: We provide evidence that PAV-TAS2R38 expression amount correlates with individual differences in bitter sensory perception and diet. The nature of this correlation calls for additional research on the molecular mechanisms associated with some individual

  16. Constraints on Mercury’s surface composition from MESSENGER and ground-based spectroscopy

    NASA Astrophysics Data System (ADS)

    Warell, J.; Sprague, A.; Kozlowski, R.; Rothery, D. A.; Lewis, N.; Helbert, J.; Cloutis, E.

    2010-09-01

    The composition and chemistry of Mercury's regolith has been calculated from MESSENGER MASCS 0.3-1.3 μm spectra from the first flyby, using an implementation of Hapke's radiative transfer-based photometric model for light scattering in semi-transparent porous media, and a linear spectral mixing algorithm. We combine this investigation with linear spectral fitting results from mid-infrared spectra and compare derived oxide abundances with mercurian formation models and lunar samples. Hapke modeling results indicate a regolith that is optically dominated by finely comminuted particles with average area weighted grain size near 20 μm. Mercury shows lunar-style space weathering, with maturation-produced microphase iron present at ˜0.065 wt.% abundance, with only small variations between mature and immature sites, the amount of which is unable to explain Mercury's low brightness relative to the Moon. The average modal mineralogies for the flyby 1 spectra derived from Hapke modeling are 35-70% Na-rich plagioclase or orthoclase, up to 30% Mg-rich clinopyroxene, <5% Mg-rich orthopyroxene, minute olivine, ˜20-45% low-Fe, low-Ti agglutinitic glass, and <10% of one or more lunar-like opaque minerals. Mercurian average oxide abundances derived from Hapke models and mid-infrared linear fitting include 40-50 wt.% SiO 2, 10-35 wt.% Al 2O 3, 1-8 wt.% FeO, and <25 wt.% TiO 2; the inferred rock type is basalt. Lunar-like opaques or glasses with high Fe and/or Ti abundances cannot on their own, or in combination, explain Mercury's low brightness. The linear mixing results indicate the presence of clinopyroxenes that contain up to 21 wt.% MnO and the presence of a Mn-rich hedenbergite. Mn in M1 crystalline lattice sites of hedenbergite suppresses the strong 1 and 2 μm crystal field absorption bands and may thus act as a strong darkening agent on Mercury. Also, one or more of thermally darkened silicates, Fe-poor opaques and matured glasses, or Mercury-unique Ostwald

  17. 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.

  18. 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.

  19. Development with MESSENGER Data of a Model of Mercury's Magnetospheric Magnetic Field Confined within the Average Observed Magnetopause

    NASA Astrophysics Data System (ADS)

    Korth, H.; Tsyganenko, N. A.; Johnson, C. L.; Philpott, L. C.; Anderson, B. J.; Al Asad, M.; Solomon, S. C.; McNutt, R. L., Jr.

    2014-12-01

    Accurate knowledge of Mercury's magnetospheric magnetic field is required to understand the sources of the planet's internal field. We present the first model of Mercury's magnetospheric magnetic field that is confined within a magnetopause shape derived from Magnetometer observations by the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft. The model consists of individual modules for magnetic fields of internal origin, approximated by a dipole of magnitude 190 nT RM3, where RM is Mercury's radius, offset northward by 479 km along the spin axis, and of external origin resulting from currents flowing on the magnetopause boundary and in the cross-tail current sheet. The cross-tail current is prescribed having a disk shape near the planet and extending into a Harris sheet at larger distances. The magnitude of the tail current is fit to minimize the root mean square residual between the magnetic field within the magnetosphere observed by MESSENGER and the model field. The magnetic field contribution from each module is shielded individually by a scalar potential function consisting of Cartesian harmonic expansions with linear and non-linear coefficients, which are fit to minimize the root-mean-square normal magnetic field component at the magnetopause. The resulting model resembles the observed magnetic field better than the previously developed paraboloid model in regions that are close to the magnetopause, i.e., at northern high latitudes and on the dayside. It will allow more accurate characterization of crustal magnetization, which may be observed during low-altitude orbits in the final months of the MESSENGER mission.

  20. 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.

  1. Comparison of the Color Properties of Selected Features on Mercury from Mariner 10 and MESSENGER Multispectral Images

    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.

    2008-12-01

    During the second flyby of Mercury by the MESSENGER spacecraft (October 6, 2008), the Mercury Dual Imaging System (MDIS) will collect high-spatial-resolution broadband and lower-spatial-resolution multispectral images. The MDIS wide-angle camera (WAC) has 11 narrow-band color filters with center wavelengths in the range 430 to 1020 nm. The portion of the planet that will be illuminated by the Sun and visible to MDIS during the spacecraft's departure trajectory includes a region that was covered by Mariner 10 two-color vidicon imagery in the ultraviolet (355 nm) and orange (575 nm), which has provided color-ratio and spectral parameter images with which a number of workers have made inferences about the composition of surface units. The region of interest is the Mariner 10 first-encounter "incoming" hemisphere. Prominent features in this area include the crater Kuiper, the Rudaki plains, the Homer basin, and the craters Lermontov and Mistral. Kuiper (62-km diameter), the base of the Kuiperian time-stratigraphic system, is superimposed on the older crater Murasaki. Kuiper has an extensive bright ray network, and spectral parameter images indicate that Kuiper has excavated material that is lower in opaque content than the typical surface in the area. The Rudaki plains are low in opaque minerals compared with the surroundings that they embay and may represent a deposit of the High Reflectance Plains (HRP) described on the basis of MESSENGER flyby 1 imagery. Dark, high-opaque material is disposed along a linear ring segment of the Homer basin and may have been emplaced by pyroclastic activity. Lermontov and Mistral have high- reflectance, blue material on their floors, which may correspond to the Bright Crater Floor Deposits (BCFDs) present in the MESSENGER first-flyby departing hemisphere. The new MESSENGER data, which offers greater wavelength range in addition to improved radiometric calibration, co-registration, and signal-to-noise ratio compared with Mariner 10

  2. A new species of the South East Asian genus Sarax Simon, 1892 (Arachnida: Amblypygi: Charinidae) and synonymization of Sarax mediterraneus Delle Cave, 1986.

    PubMed

    Seiter, Michael; Wolff, Jonas; Hörweg, Christoph

    2015-01-01

    A new species of the whip spider genus Sarax Simon, 1892 from Cebu Island in the Philippines is described: Sarax huberi sp. nov. With the description of this species, the diversity of the genus is increased to three species in the Philippines. Some additional data on their natural environment and their specific habitat are presented and compared with sibling species. The synonymization of Sarax mediterraneus Delle Cave, 1986 with Sarax buxtoni (Gravely, 1915) is carried out. PMID:26623874

  3. Mobile healthcare informatics.

    PubMed

    Siau, Keng; Shen, Zixing

    2006-06-01

    Advances in wireless technology give pace to the rapid development of mobile applications. The coming mobile revolution will bring dramatic and fundamental changes to our daily life. It will influence the way we live, the way we do things, and the way we take care of our health. For the healthcare industry, mobile applications provide a new frontier in offering better care and services to patients, and a more flexible and mobile way of communicating with suppliers and patients. Mobile applications will provide important real time data for patients, physicians, insurers, and suppliers. In addition, it will revolutionalize the way information is managed in the healthcare industry and redefine the doctor - patient communication. This paper discusses different aspects of mobile healthcare. Specifically, it presents mobile applications in healthcare, and discusses possible challenges facing the development of mobile applications. Obstacles in developing mobile healthcare applications include mobile device limitations, wireless networking problems, infrastructure constraints, security concerns, and user distrust. Research issues in resolving or alleviating these problems are also discussed in the paper. PMID:16777784

  4. Social mobility and fertility.

    PubMed

    Kasarda, J D; Billy, J O

    1985-01-01

    This review examines 4 possible causal links between social mobility and fertility: 1) fertility affects social mobility; 2) social mobility affects fertility; 3) fertility and social mobility simultaneously affect each other; and 4) social mobility and fertility are unrelated. Due to the lack of systematic theory guiding the research, conceptualizations and measures of social mobility and fertility vary markedly from study to study, leading to inconsistent findings. The review focuses on theoretical perspectives underpinning the research, causal operators proposed to interpret observed associations, and analytical methods used. The selectivity perspective is based on the contention that a family must be small in order to rise on the social scale. This has found little support, however. In fact, studies suggest that children induce slightly higher levels of status achievement and family responsibilities may stimulate the energy and ambition of some so that they achieve more than they would have done without a family. Most studies have concerned the hypothesis that social mobility affects fertility. 4 theoretical perspectives have emerged: status enhancement; relative economic status; social isolation; and stress and disorientation. At any time in a couple's reproductive life cycle the decision or actual experience of either social mobility or fertility may influence the decision or actual experience of the other variable. Mobility-fertility research has defined an individual's or couple's position in terms of income, education, or occupation with occupation used most often as a single index of social class and indexes of social mobility developed by comparing persons' changes in occupational position. A common theme in much of the research literature is that the existence of an effect of social mobility on fertility depends on the societal conditions of a given population. Most studies through the mid-60s used a common measurement method to assess whether a

  5. 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,

  6. 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.

  7. 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.

  8. Calcium and cyclic adenosine monophosphate as second messengers for vasopressin in the rat inner medullary collecting duct.

    PubMed Central

    Star, R A; Nonoguchi, H; Balaban, R; Knepper, M A

    1988-01-01

    Vasopressin increases both the urea permeability and osmotic water permeability in the terminal part of the renal inner medullary collecting duct (terminal IMCD). To identify the second messengers that mediate these responses, we measured urea permeability, osmotic water permeability, intracellular calcium concentration, and cyclic AMP accumulation in isolated terminal IMCDs. After addition of vasopressin, a transient rise in intracellular calcium occurred that was coincident with increases in cyclic AMP accumulation and urea permeability. Half-maximal increases in urea permeability and osmotic water permeability occurred with 0.01 nM vasopressin. The threshold concentration for a measurable increase in cyclic AMP accumulation was approximately 0.01 nM, while measurable increases in intracellular calcium required much higher vasopressin concentrations (greater than 0.1 nM). Exogenous cyclic AMP (1 mM 8-Br-cAMP) mimicked the effect of vasopressin on urea permeability but did not produce a measurable change in intracellular calcium concentration. Conclusions: (a) Cyclic AMP is the second messenger that mediates the urea permeability response to vasopressin in the rat terminal IMCD. (b) Vasopressin increases the intracellular calcium concentration in the rat terminal IMCD, but the physiological role of this response is not yet known. PMID:2838523

  9. An essential role for an inositol polyphosphate multikinase, Ipk2, in mouse embryogenesis and second messenger production

    PubMed Central

    Frederick, Joshua P.; Mattiske, Deidre; Wofford, Jessica A.; Megosh, Louis C.; Drake, Li Yin; Chiou, Shean-Tai; Hogan, Brigid L. M.; York, John D.

    2005-01-01

    Phospholipase C and several inositol polyphosphate kinase (IPK) activities generate a branched ensemble of inositol polyphosphate second messengers that regulate cellular signaling pathways in the nucleus and cytoplasm. Here, we report that mice deficient for Ipk2 (also known as inositol polyphosphate multikinase), an inositol trisphosphate and tetrakisphosphate 6/5/3-kinase active at several places in the inositol metabolic pathways, die around embryonic day 9.5 with multiple morphological defects, including abnormal folding of the neural tube. Metabolic analysis of Ipk2-deficient cells demonstrates that synthesis of the majority of inositol pentakisphosphate, hexakisphosphate and pyrophosphate species are disrupted, although the presence of 10% residual inositol hexakisphosphate indicates the existence of a minor alternative pathway. Agonist induced inositol tris- and bis-phosphate production and calcium release responses are present in homozygous mutant cells, indicating that the observed mouse phenotypes are a result of failure to produce higher inositol polyphosphates. Our data demonstrate that Ipk2 plays a major role in the synthesis of inositol polyphosphate messengers derived from inositol 1,4,5-trisphosphate and uncovers a role for their production in embryogenesis and normal development. PMID:15939867

  10. 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.

  11. 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.

  12. Making Sense of 2.5 Million Surface Reflectance Spectra of Mercury from MESSENGER

    NASA Astrophysics Data System (ADS)

    D'Amore, M.; Helbert, J.; D'Incecco, P.; Domingue, D. L.; Izenberg, N. R.; McClintock, W. E.

    2012-12-01

    The Mercury Atmospheric and Surface and Composition Spectrometer (MASCS) on the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft has mapped the surface of Mercury on a global basis during its one-year primary orbital mission and the first third of its extended mission, producing ~2.5 million spectra from March 2011 to July 2012. The primary challenge to analyzing this dataset is to cope with its large size. In earlier studies of MASCS data, we combined several approaches, ranging from principal component analysis (PCA) to unsupervised cluster analysis and regridding to global and local fixed grids. Each of those techniques provided insight into spectral variations for different volumes of data, but each was quickly overcome by the growing dataset. The most recent version of our data analysis procedure uses PostgreSQL, a type of database management that controls the creation, integrity, maintenance, and use of a database. It embeds a high-level query language, which greatly simplifies database organization as well as retrieval and presentation of database information. We set up a data pipeline to update automatically the MASCS data, read them from the NASA Planetary Data System format, regrid the data to a common grid length, and store all information in the database. All data are then readily available to any authorized user in our network. We are working on a library to access the data directly from within our analysis software, and some preliminary functions have been implemented. As an example, the calculation of a parameter representing the database takes 2 s even for the full dataset of 2.5 million entries. It is thus straightforward to create and analyze rapidly the data, as for example the distribution of normalized radiance at a fixed wavelength. The new methodology provides facilities for controlling data access, enforcing data integrity, managing concurrency control, and recovering the database after a failure and

  13. 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

  14. Venus Measurements by the MESSENGER Gamma-Ray and X-Ray Spectrometers

    NASA Astrophysics Data System (ADS)

    Rhodes, E. A.; Starr, R. D.; Goldsten, J. O.; Schlemm, C. E.; Boynton, W. V.

    2007-12-01

    The Gamma-Ray Spectrometer (GRS), which is a part of the Gamma-Ray and Neutron Spectrometer Instrument, and the X-Ray Spectrometer (XRS) on the MESSENGER spacecraft made calibration measurements during the Venus flyby on June 5, 2007. The purpose of these instruments is to determine elemental abundances on the surface of Mercury. The GRS measures gamma-rays emitted from element interactions with cosmic rays impinging on the surface, while the XRS measures X-ray emissions induced on the surface by the incident solar flux. The GRS sensor is a high-resolution high-purity Ge detector cooled by a Stirling cryocooler, surrounded by a borated-plastic anticoincidence shield. The GRS is sensitive to gamma-rays up to ~10 MeV and can identify most major elements, sampling down to depths of about ten centimeters. Only the shield was powered on for this flyby in order to conserve cooler lifetime. Gamma-rays were observed coming from Venus as well as from the spacecraft. Although the Venus gamma-rays originate from its thick atmosphere rather than its surface, the GRS data from this encounter will provide useful calibration data from a source of known composition. In particular, the data will be useful for determining GRS sensitivity and pointing options for the Mercury flybys, the first of which will be in January 2008. The X-ray spectrum of a planetary surface is dominated by a combination of the fluorescence and scattered solar X-rays. The most prominent fluorescent lines are the Kα lines from the major elements Mg, Al, Si, S, Ca, Ti, and Fe (1-10 keV). The sampling depth is less than 100 u m. The XRS is similar in design to experiments flown on Apollo 15 and 16 and the NEAR-Shoemaker mission. Three large-area gas-proportional counters view the planet, and a small Si-PIN detector mounted on the spacecraft sunshade monitors the Sun. The energy resolution of the gas proportional counters (~850 eV at 5.9 keV) is sufficient to resolve the X-ray lines above 2 keV, but Al and Mg

  15. Implications of the MESSENGER Discovery of High Sulfur Abundance on the Surface of Mercury

    NASA Astrophysics Data System (ADS)

    Zolotov, M. Y.; Sprague, A. L.; Nittler, L. R.; Weider, S. Z.; Starr, R. D.; Evans, L. G.; Boynton, W. V.; Goldsten, J. O.; Hauck, S. A.; Solomon, S. C.

    2011-12-01

    The unusually high S content detected in Mercury's surface materials with the MESSENGER X-ray Spectrometer (XRS) constrains surface mineralogy, petrology, and the redox state of magmas and rocks. This discovery along with the low FeO content in surface silicates indicates a low oxygen fugacity (fO2) in corresponding melts and the occurrence of S in sulfides, which could be abundant in surface rocks. The detected high S content could reflect anomalously high (up to 8-10 wt%) solubility of sulfide S in extremely reduced magmas. The high bulk S/Fe ratio also suggests the presence of S in sulfides of Mg, Ca, Mn, and Cr, which occur in enstatite chondrites. Although the presence of some troilite (FeS) is possible, niningerite, (Mg, Fe, Mn)S, could be the most abundant sulfide. Niningerite could be partially responsible for Mercury's low surface albedo, its unusual reflectance spectrum at visible and near-infrared wavelengths, and the relatively high neutron absorption, because Mn is a strong neutron absorber. The presence of abundant niningerite would also imply a lower Mg/Si ratio in silicates than in bulk surface materials. It follows that Mg-rich mafic lavas could be present instead of, or in addition to, ultramafic lavas (komatiites). The occurrence of Mg-silicates (enstatite and forsterite) in Mercury's regolith as inferred from mid-infrared spectroscopy, together with the postulated presence of niningerite, helps characterize fO2 and fS2 in corresponding melts. If fS2 is controlled by the Fe-metal-Fe-sulfide equilibrium, the silicate-sulfide equilibria set fO2 values. For temperature less than 1700 K the evaluated values are less than 5.5 log fO2 units below the iron-wüstite buffer (IW-5.5). Lower temperatures and analogous considerations for Ca and Mn silicate-sulfide equilibria lead to lower fO2 values. For Fe-metal-saturated melts at 1700 K the fO2 value is IW-5.5 and corresponds to ~0.1 mol % FeO, which could be considered as an upper limit in magmas and

  16. 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

  17. 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.

  18. 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.

  19. Mobile computing for radiology.

    PubMed

    Auffermann, William F; Chetlen, Alison L; Sharma, Arjun; Colucci, Andrew T; DeQuesada, Ivan M; Grajo, Joseph R; Kung, Justin W; Loehfelm, Thomas W; Sherry, Steven J

    2013-12-01

    The rapid advances in mobile computing technology have the potential to change the way radiology and medicine as a whole are practiced. Several mobile computing advances have not yet found application to the practice of radiology, while others have already been applied to radiology but are not in widespread clinical use. This review addresses several areas where radiology and medicine in general may benefit from adoption of the latest mobile computing technologies and speculates on potential future applications. PMID:24200475

  20. 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.

  1. Doctors going mobile.

    PubMed

    Romano, Ron; Baum, Neil

    2014-01-01

    Having a Web page and a blog site are the minimum requirements for an Internet presence in the new millennium. However, a Web page that loads on a personal computer or a laptop will be ineffective on a mobile or cellular phone. Today, with more existing and potential patients having access to cellular technology, it is necessary to reconfigure the appearance of your Web site that appears on a mobile phone. This article discusses mobile computing and suggestions for improving the appearance of your Web site on a mobile or cellular phone. PMID:25807610

  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. 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…

  4. Mobile Marine Museum.

    ERIC Educational Resources Information Center

    Bauer, R. D.; Schaadt, M. S.

    1984-01-01

    Calfiornia State University (Long Beach) purchased a motor home and converted it into a mobile marine science display unit, outfitting it with built-in display racks inside and an awning to provide shelter displays suited to outdoor use. School activities and programs using the mobile museum are described. (JN)

  5. 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,…

  6. 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…

  7. ACTS Mobile Terminals

    NASA Technical Reports Server (NTRS)

    Abbe, Brian S.; Agan, Martin J.; Jedrey, Thomas C.

    1997-01-01

    The development of the Advanced Communications Technology Satellite (ACTS) Mobile Terminal (AMT) and its follow-on, the Broadband Aeronautical Terminal (BAT), have provided an excellent testbed for the evaluation of K- and Ka-band mobile satellite communications systems. An overview of both of these terminals is presented in this paper.

  8. 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…

  9. 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…

  10. 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.

  11. Extravehicular mobility unit

    NASA Technical Reports Server (NTRS)

    Carson, M. A.; Rouen, M. N.; Lutz, C. C.; Mcbarron, J. W., II

    1975-01-01

    The Apollo extravehicular mobility unit (EMU) consisted of a highly mobile, anthropomorphic pressure vessel and a portable life support system. The EMU used for the first lunar landing is described along with the changes made in the EMU design during the program to incorporate the results of experience and to provide new capabilities. The performance of the EMU is discussed.

  12. 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.

  13. 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…

  14. 33 CFR 165.835 - Security Zone; Port of Mobile, Mobile Ship Channel, Mobile, AL.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... definition covers passenger vessels that must comply with 33 CFR parts 120 and 128. (b) Location. The..., 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...

  15. 33 CFR 165.835 - Security Zone; Port of Mobile, Mobile Ship Channel, Mobile, AL.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... definition covers passenger vessels that must comply with 33 CFR parts 120 and 128. (b) Location. The..., 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...

  16. 33 CFR 165.835 - Security Zone; Port of Mobile, Mobile Ship Channel, Mobile, AL.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... definition covers passenger vessels that must comply with 33 CFR parts 120 and 128. (b) Location. The..., 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...

  17. Radioactive Elements on Mercury’s Surface from MESSENGER: Implications for the Planet’s Formation and Evolution

    NASA Astrophysics Data System (ADS)

    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.

    2011-09-01

    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.

  18. THEMIS Na exosphere observations of Mercury and their correlation with in-situ magnetic field measurements by MESSENGER

    NASA Astrophysics Data System (ADS)

    Mangano, V.; Massetti, S.; Milillo, A.; Plainaki, C.; Orsini, S.; Rispoli, R.; Leblanc, F.

    2015-10-01

    The Na exosphere of Mercury is being studied since its discovery in mid '80s from Earth-based telescopes, and it has revealed a high dynamics and variability. Although the processes and their relationships characterising the Hermean exosphere generation and dynamics are still not exhaustively understood, there are no doubts on a tight interconnection among the planet's surface, exosphere, intrinsic magnetic field, the Solar Wind and the Interplanetary Magnetic Field (IMF). Here we analyse an extended dataset of images of the exospheric Na emission, collected from 2009 to 2013, by means of the THEMIS groundbased telescope, and perform a comprehensive statistical study of the recurrent Na emission patterns, and also their potential relationship with the IMF variability. For this purpose, we take advantage of a subset (years 2011-2013) of contemporary in situ measurements of the IMF obtained by the MAG instrument on-board the MESSENGER spacecraft.

  19. High mobility of landslides on the Mercury crater rims

    NASA Astrophysics Data System (ADS)

    Fukuoka, H.; Kadota, N.; Kiritoshi, I.; Sugiyama, H.; Uragami, H.

    2013-12-01

    The NASA's MESSENGER mercury spacecraft was launched by NASA in 2004, and orbital insertion was successfully completed in 2011. Among its scientific instruments, the Mercury Dual Imaging System (MDIS) and the Mercury Laser Altimeter (MLA) are used to extract the mercury terrain topography. This mission revealed various features of the mercury topography with horizontal resolution of 1 km. Up to July 2013, elevation of the north hemisphere terrain had been released on the net (Quickmap: http://messenger-act.actgate.com/msgr_public_released/react_quickmap.html). As reported by previous studies on landslides found on the lunar crater rims (Fukuoka et al., 2011), they showed extremely small H/V = tan (apparent friction) of the movement, even though almost no groundwater could have been expected ever. Authors examined the crater rims in the northern hemisphere of latitude higher than 65 degrees, because the precision of the altitude is higher in the polar and equatorial regions. We found as many similar landslides along the crater rims. Then, in order to compare the mobility of landslides with lunar ones, we have examined the apparent friction (H/T). In most cases, the H/T values of those landslides are between 0.1 and 0.2, like long-runout landslides on the Moon, Mars and Earth. If the rocks on the mercury show the similar friction as rocks on the earth, those values should be higher than 0.5. Possible mechanism of the small H/L could be cumulated shear displacement induced by repeated quakes by meteor impact over billions of years and / or exotic mechanism including tectonic function.

  20. 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.

  1. 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.

  2. 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

  3. 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.

  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. PMID:23576719

  5. Mobile Lunar Base Concepts

    NASA Astrophysics Data System (ADS)

    Cohen, Marc M.

    2004-02-01

    This paper describes three innovative concepts for a mobile lunar base. These concept combine design research for habitat architecture, mobility systems, habitability, radiation protection, human factors, and living and working environments on the lunar surface. The mobile lunar base presents several key advantages over conventional static base notions. These advantages concern landing zone safety, the requirement to move modules over the lunar surface, and the ability to stage mobile reconnaissance with effective systemic redundancy. All of these concerns lead to the consideration of a mobile walking habitat module and base design. The key issues involve landing zone safety, the ability to transport habitat modules across the surface, and providing reliability and redundancy to exploration traverses in pressurized vehicles. With self-ambulating lunar base modules, it will be feasible to have each module separate itself from its retro-rocket thruster unit, and walk five to ten km away from the LZ to a pre-selected site. These mobile modules can operate in an autonomous or teleoperated mode to navigate the lunar surface. At the site of the base, the mobile modules can combine together; make pressure port connections among themselves, to create a multi-module pressurized lunar base.

  6. 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

  7. 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

  8. 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

  9. Understanding Mobile Apps

    MedlinePlus

    ... of Old Computers Disposing of Your Mobile Device Laptop Security Malware P2P File-Sharing Risks Phishing Securing ... to Help You Shop in Stores Hacked Email Laptop Security Bookmark Shopping Online with Virtual Currencies infographic ...

  10. 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 ...

  11. 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.

  12. 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.

  13. REST based mobile applications

    NASA Astrophysics Data System (ADS)

    Rambow, Mark; Preuss, Thomas; Berdux, Jörg; Conrad, Marc

    2008-02-01

    Simplicity is the major advantage of REST based webservices. Whereas SOAP is widespread in complex, security sensitive business-to-business aplications, REST is widely used for mashups and end-user centric applicatons. In that context we give an overview of REST and compare it to SOAP. Furthermore we apply the GeoDrawing application as an example for REST based mobile applications and emphasize on pros and cons for the use of REST in mobile application scenarios.

  14. 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.

  15. Mobile Uninterruptible Power Supply

    NASA Technical Reports Server (NTRS)

    Mears, Robert L.

    1990-01-01

    Proposed mobile unit provides 20 kVA of uninterruptible power. Used with mobile secondary power-distribution centers to provide power to test equipment with minimal cabling, hazards, and obstacles. Wheeled close to test equipment and system being tested so only short cable connections needed. Quickly moved and set up in new location. Uninterruptible power supply intended for tests which data lost or equipment damaged during even transient power failure.

  16. 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.

  17. 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.

  18. 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…

  19. Mobile medical image retrieval

    NASA Astrophysics Data System (ADS)

    Duc, Samuel; Depeursinge, Adrien; Eggel, Ivan; Müller, Henning

    2011-03-01

    Images are an integral part of medical practice for diagnosis, treatment planning and teaching. Image retrieval has gained in importance mainly as a research domain over the past 20 years. Both textual and visual retrieval of images are essential. In the process of mobile devices becoming reliable and having a functionality equaling that of formerly desktop clients, mobile computing has gained ground and many applications have been explored. This creates a new field of mobile information search & access and in this context images can play an important role as they often allow understanding complex scenarios much quicker and easier than free text. Mobile information retrieval in general has skyrocketed over the past year with many new applications and tools being developed and all sorts of interfaces being adapted to mobile clients. This article describes constraints of an information retrieval system including visual and textual information retrieval from the medical literature of BioMedCentral and of the RSNA journals Radiology and Radiographics. Solutions for mobile data access with an example on an iPhone in a web-based environment are presented as iPhones are frequently used and the operating system is bound to become the most frequent smartphone operating system in 2011. A web-based scenario was chosen to allow for a use by other smart phone platforms such as Android as well. Constraints of small screens and navigation with touch screens are taken into account in the development of the application. A hybrid choice had to be taken to allow for taking pictures with the cell phone camera and upload them for visual similarity search as most producers of smart phones block this functionality to web applications. Mobile information access and in particular access to images can be surprisingly efficient and effective on smaller screens. Images can be read on screen much faster and relevance of documents can be identified quickly through the use of images contained in

  20. 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